Butterflies and Moths (British)

If you reside on the outskirts of a town an occasional tour of inspection of street lamps may add a few specimens to your collection, and some entomologists attach so much importance to the value of these luminaries that they provide themselves with a special net for the removal of moths from the glass and rails (fig. 50). The straight side marked a is applied to the panes of glass when flutterers or settlers are to be taken, and the bend on the opposite side is to secure those that rest on the rail. Such a frame is easily made by bending a piece of stout wire to the required shape, and then soldering it to a ferrule to receive a long stick. The net itself should not be deep.

Many different forms of traps are now made for catching moths, and these are deservedly coming rapidly into favour. They are generally constructed on a 'catch-'em-alive-oh' principle, and have the advantage that, after having been set, they may be left alone all night without any watching, and give an ambitious collector the opportunity of taking insects in his garden and searching in the open field both at the same time.

One of these traps may be constructed as follows at the cost of only a few pence over the price of a small paraffin lamp. Put together a square box, the sides about two feet and the front open, or procure a suitable one from your grocer. Place a paraffin lamp with a bright tin reflector at the back of this, and make a hole in the top just over the chimney to allow the heated air to pass out freely. Three sheets of glass are now to be placed as shown in the sketch (fig. 51), one upright piece completely shutting off the lamp, and two others placed obliquely with a space between them just large enough to allow admission. These must be exactly the width of the box, and should not be permanently fixed, but simply resting on small wooden supports nailed on to the sides. When required for use, it is only necessary to light up the lamp, strew some dead leaves on the bottom of the box, and put the sheets in their places. It will be seen at once that the angles at which they are placed will direct all light-seekers into the lower compartment, whence they are not at all likely to find their way out again; and after vain endeavours to reach the light they finally settle down on the sides of the box or seek shelter among the dead leaves.

For such out-door work in search of moths a good lantern is essential. An ordinary 'bull's-eye' is almost useless, for, although it concentrates a good light on certain objects, the narrow range of its rays constitutes a strong objection to its use for entomological work. For this purpose it is necessary that the rays of light not only pass in front of you, but also shoot off right and left to warn you of the approach of a moth before it is too late to wield the net. This wide range may be obtained by means of three flat glass sides, or, better still, by a bent plate glass front.

In addition to this you must go out provided with your net, killing bottle, and a number of pill boxes. Choose your night according to the hints already given, and if you are on the look-out for any particular species, be careful that the date of your outing is well timed, making any necessary allowances for the forwardness or backwardness of the season, for a moth that is generally due on a certain average time of the year may appear some weeks sooner if the preceding weeks have been unusually warm, or its emergence may be delayed considerably by the prevalence of cold east winds or a late frost.

Make up your mind as to the field of your operations before you start, and if possible choose a route that will carry you through a variety of situations, so that you may pass the favourite haunts of a number of different species. Clearings in woods with an abundant undergrowth, waste places with plenty of tall and rank vegetation, overgrown railway banks, clover fields, the flowery borders of corn fields, plantations in parks, heaths and moors, sheltered and overgrown hollows such as chalk pits and old disused quarries, reed and marsh land, all these are good localities, each one inhabited by its own peculiar species, and if your route runs through a fair variety of such places you may, other things being equally favourable, depend on a good catch.

See that your time also is well chosen. Of course you cannot say exactly what the night will be till it actually comes, and, as you have to start off before it is dark, you must consider the probabilities of the future from the present condition of the air. Let it be a night when a bright moon is not due, and if it follow a warm and moist day with a south or south-west wind, or if drizzly, so much the better; but let your feet be shod with boots that will permit you to wade through moist herbage without danger, and take a waterproof if necessary.

It is always advisable to be on your hunting ground before twilight sets in, as a number of moths venture out before the sun has disappeared; and then you can work on till midnight if you feel inclined, or even extend your labours till the early hours of the morning.

Before dusk you will meet with many of the little Tortrices (page 298) in sheltered spots, and a little later the Geometræ and Hawks will be on the wing. Thus, before dark, you may make good use of your net, dealing with your captures just in the same way as recommended in the case of butterflies.

After a time, however, the lantern will have to be brought to your assistance in making known the whereabouts of the later species, consisting chiefly of the Noctuæ, many of which do not make their appearance till it is quite dark. If now you carry your lantern in your left hand, your work will be rendered somewhat difficult and tedious, for, although one hand is sufficient to manage the net properly, you are compelled to rest your light on the ground every time you make a capture, as it is impossible to box your specimens unless both hands are quite free. This difficulty is easily overcome by suspending the lantern by means of a string or strap placed round your neck, allowing it to hang on your chest; and a further advantage is gained by having a second strap round your chest to prevent it from swaying about with every movement of your body. This arrangement gives you both hands perfectly free during the whole time, and also prevents the necessity of continually bringing yourself into a stooping or kneeling posture while you are examining or boxing the specimens you have netted.

There are now two courses open to you. Either you can kill and pin the moths as you catch them, fixing each one securely in the collecting box, or you may simply shut each one in a separate pill box and leave the remainder of the work to be done at home. If the ordinary collecting box only is used, a little of your time is necessarily occupied in pinning and transferring, and if many insects are about such an occupation may appear to you to be a waste of valuable time. But this is not all. Often and often will you find that while thus engaged a splendid moth will come and flutter round your light; and, before you have time to drop your collecting box and pick up the net, the fine creature you would have prized has darted off again. This certainly seems to speak in favour of the pill-boxing method, but it must be remembered that a few of the moths will continue to flutter after they have been boxed, so that when you arrive home they are more or less damaged, a large number of the scales that once adorned the wings now lying on the sides and bottom of the boxes. Perhaps the best plan is to take both the collecting box and also a quantity of pill boxes, and a little experience will soon show you which is the better accommodation for certain kinds.

Particular attention must be paid to flowers, some of which are very attractive to the Noctuæ especially. Sallow blossom in spring and ivy bloom in autumn should be carefully and frequently watched, and at other times the blossoms of heather, ragwort, bramble, clover, and various other flowers must be searched.

As you cast the rays of the lantern on the feasting moths some will prove themselves very wary, and dart away at your approach; but others will take but little notice of your advance, and will continue to suck the sweet nectar, their eyes glaring like living sparks.

As a rule the Noctuæ thus engaged are easily pill-boxed or caught direct in the cyanide bottle; but a few of the more restless species are to be made sure of only by a sweep of the net. Some will feign death as soon as disturbed, and allow themselves to drop among the foliage, where further search is generally fruitless.

Another common difficulty arises from the inconvenient height of many of the attractive blossoms—often so great that it is impossible to reach them with the net, and very difficult to direct the rays of your lantern on them. This is particularly the case with sallow and ivy, the flowers of which are two rich sources of supply to the entomologist.

Those who intend giving special attention to these blossoms should be provided with some form of apparatus that will enable them to extend their operations as high as possible. Perhaps the most effective arrangement is the well-known combination here figured. It consists of a long and stout stick, at the top of which is a tubular joint (fig. 52) that might be termed a T-piece were it not that the smaller part does not stand out at right angles to the other. In this is fixed, in a straight line with the stick, a short rod on which hangs a lantern—an ordinary bull's-eye answers well here; and in the smaller tube is another short rod carrying a shallow basin-shaped net, and of such a length that the net is just in advance of the lantern.

At first sight this arrangement will strike you as being very unsatisfactory, there being no kind of trap to prevent the escape of the insects. But it must be remembered that moths are more or less addicted to habits of intemperance—that they will hold on to the supply of the sweet fluid they enjoy till they are ready to drop with intoxication. This being the case, some will fall into your net as soon as they are startled by the sudden and near approach of the glare of your lamp, and others are easily made to fall therein by gently tapping the flower-bearing stems from below with the edge of the ring.

Having become acquainted with this very sad propensity, which thus brings ruin to so many unfortunate moths, can we not yet further turn their evil doings to our own profit in our endeavours to become acquainted with their structure and history? Most certainly we can. All we have to do is to distribute in their haunts a bountiful supply of some artificial intoxicant such as they love, and then lie in wait for the victims that fall a prey to our snare. This process is known to entomologists as 'sugaring,' and is a splendid means of securing an abundance of species, often including some rare ones that are scarcely to be obtained by any other plan. Let us now inquire into the modus operandi of this interesting operation.

The first thing to do is to prepare the luring sweetmeat. Supply yourself with a quantity of strong, dark treacle, and also some dark brown sugar; always remembering, in the selection of these viands, that odour rather than purity is to be the guide. The best kinds of sugar are those very dark and moist brands imported in a raw state from the West Indies, nothing being better than that known as 'Jamaica Foots.'

Mix about equal quantities of these with a little stale beer, and boil and stir till all the sugar is dissolved. The consistency of the mixture should be such that it will work well with a brush when used as a paint—not too thick, nor so thin that it is easily absorbed by the substance on which it is 'painted,' nor must it be in such a fluid condition that it easily runs.

When satisfied on these points, transfer the mixture to a tin canister, see it properly covered, and set it aside as your 'stock' from which you can draw supplies as required. Now secure an ordinary painter's brush of convenient size, and a number of strips of linen or other rag, each one of which is fastened to a hook formed of bent wire. These items, together with the usual lantern, collecting box, pill boxes, and killing bottle, complete your outfit for the sugaring expedition.

When the selected time for operations has arrived, take sufficient 'sugar' for your night's work, mix it well with sufficient strong rum to give it a very decided odour, and start off at dusk with this and the other requisites just mentioned.

The night chosen should be warm and calm, with a rather damp atmosphere, and no moon preferred. Let your locality be a well-wooded one; abounding, if possible, with giant oaks and other trees, and containing open spaces with plenty of underwood and rank herbage. Such localities are to be met with at their best in forest lands, and if you would do wonders at sugaring you cannot do better than arrange for spending your holidays in such a spot as the New Forest, taking with you sufficient 'sugar' for several nights' work.

Having reached a likely spot of no very great extent, you prepare for real work. Light up the lamp, and get out your sugaring tin and brush ready for action. Take your course along some definite track that you are sure to remember, painting vertical strips of sugar, about a foot long, on the trunks of trees or on palings, and hanging strips of rag that have just been steeped in the sugar on the branches of small trees and shrubs where you do not find good surfaces for the brush.

After satisfying yourself concerning the amount of sugar distributed, retrace your steps, examining every patch of sugar as you go. It will not be long before signs of life appear. Earwigs, spiders, centipedes and slugs will soon search out the luscious feast, but unless the time and the locality are ill chosen, the lantern will soon reveal a goodly number of moths, with eyes glaring like little balls of fire, greedily devouring the bounteous repast. These will consist chiefly of Noctuæ, but Sphinges, Geometræ and numerous small species also join the company.

Some will exhibit a restless disposition, either darting off before you make a close approach, or keeping their wings in rapid vibration as if to be fully prepared for a hasty retreat when occasion demands. These must receive your attention first; and, having secured them, proceed to box as many as you require of the more lazy and gluttonous species.

As a rule, moths thus engaged are easily pill-boxed, but the livelier ones will not submit to such treatment without attempting to escape. The best way to secure these is either to cover them with the opened cyanide bottle (or its substitute), and replace the cork as soon as a favourable opportunity occurs; or to perform the same feat with a glass-bottomed pill box.

The advantage of the latter over the ordinary boxes will be seen at once. After the insect is covered, its movements can be watched, and so a favourable opportunity can be seized for snapping on the lid.

As already stated, some moths feign death when in danger, allowing themselves to fall in places where they are often quite safe from capture. Others allow themselves to fall simply because they have so gorged themselves with the intoxicating sweet that they can no longer maintain their hold. Both these classes of sugar seekers may easily be secured by means of a net commonly known as the 'sugaring net.'

This implement is so simple in its construction that anyone can easily make his own. The frame may consist of two straight wires or canes fixed in a metal Y, and the other ends joined by a piece of strong string or catgut as shown in fig. 54. The net itself need not be deep. As soon as you reach a tree where moths are feeding on the sugar, press the string of the net against the bark just below them. The string at once assumes the form of the trunk so well that you may be sure of every insect that falls while you are boxing.

For this work both hands must be free, and this is easily managed in spite of the number of appliances called into service. The lantern is slung round your neck and secured by a strap round the chest. The 'sugaring net' has a very short stick, and just while you are engaged in boxing specimens, it may be gently held against the trunk by a slight pressure of the body. But such precautions as these are necessary only when the night worker is out alone. There are many circumstances, however, that render the work of two or more in company much more enjoyable than that of a single-handed entomologist. The labours are considerably expedited where a division enables each one of the night ramblers to take a particular portion of the work; and if there is such a person as a nervous entomologist, that individual should on no account go a sugaring in lonely spots on dark nights. Every rustling leaf gives such a one a start; all footsteps are those of approaching disturbers of the peace; and when at last the invisible landowner or his keeper, attracted by the mysterious movements of the lamp, greets him with his gruff 'What's your business here?' then for the moment he forgets his enchanting hobby and wishes he were safely at home.

It is certainly advisable to take a friend, whether an entomologist or not, on such expeditions; and if you intend working on private grounds, always make previous arrangements with the property owner, that you may fear no foes and dread no surprises; for a sugarer is far more sure of success in his work if he keeps a cool head and has nothing to think about for the time being but his moths and his boxes.

A few hours at this interesting employment pass away very rapidly, and when midnight arrives there is often no great desire to leave off, especially when it is known that some species of moths are not very busy till very late at night. Still it is not advisable to surfeit oneself with even the sweets of life. Perhaps it is better as a rule to work the early species only on one night, and reserve another for the later ones. The searchings are then always carried on with vigour throughout, and the labours that are thus never made laborious ever retain their attractiveness in the future.

It has often been observed that, when sugaring has been carried on for a few successive nights in the same locality, the success is greater each night than on the one preceding it. Hence it is a common practice to work a chosen 'run' for two, three, or more nights in succession; and some collectors even go so far as to lay on the bait for a night or two previous to starting work. For the same reason it is often advisable to continue the use of a fairly productive beat rather than to wander in search of a new one.

In the neighbourhood of large towns one may often meet with patches of sugared bark that mark the course and extent of a brother entomologist's beat, and such are valuable to an inexperienced amateur in that they give him some idea of the nature of the localities that are chosen by more expert collectors. But it must be remembered that each entomologist has a moral right to a run he has baited, and that it is considered ungentlemanly, if not unjust, to take insects from sugar laid by another. I have sometimes seen cards, bearing the names of the collectors and the date of working, tacked on to baited trees and fences, thus establishing their temporary exclusive rights to the use of their runs. Such precautions are not necessary in large tracts of forest land, where the choice of runs is practically unlimited.

There are two other modes of capture available to the moth collector—the use of decoy females, and the employment of 'sugar traps'—and both these may be used on the sugaring run, or at other times either in the woods or in your own garden.

Procure a large cylindrical tin box, and cut a circular piece of perforated zinc just small enough to drop into it. Then make two wire rings, one a little larger than the top of the tin, and the other only about an inch in diameter. Next make a conical net of leno, open at both ends, and of such a size that the two rings may form the frames of its two extremities. When the trap is required for use, cut a circular piece of flannel or other absorbent, steep it in sugar that has just been flavoured with rum, and place it in the bottom of the tin. Then place a few pebbles of equal size around the sides to support the zinc partition, drop in the partition, and then allow the net to hang on the rim as shown in the sketch.

This arrangement will explain itself. The moths, attracted by the sweet perfume, flutter about in the net till at last they find their way through the small ring. Once in, they make further attempts to reach the sugar; and, at last, finding all efforts fruitless, and, like Paddy at the fair, not being able to discover the 'entrance out,' they finally settle down in a disappointed mood awaiting your pleasure.

Perhaps another word of explanation is necessary here. Why not allow the poor creatures to reach the sugar that attracted them to the spot? The reason is this. They sometimes gorge themselves to such an extent that their bodies, dilated to the fullest capacity with syrup, are a bit troublesome when the insects are placed in the cabinet. It is therefore advisable to see that the zinc is so far above the sugar that the moths are unable to reach the latter by thrusting their extended proboscides through the perforations. A few dead leaves scattered on the zinc is also a useful addition, since it affords shelter to such of the insects as prefer it.

This is a very useful trap to keep in one's garden throughout the season. It may not attract large numbers, but it has the advantage that it requires no watching. It is simply necessary to set it at dusk, and remove the captives in the morning or at your leisure.

CHAPTER VII
COLLECTING OVA, LARVÆ, AND PUPÆ

These portions of an entomologist's work certainly take up a great deal of his time, and also require much patience and perseverance; but the advantages derived cannot be over-estimated, for in addition to the knowledge gained of the early stages of insect life, this kind of work will enable him to place in his cabinet a number of gems he would otherwise have not and probably know not. Occasionally a prize may be obtained in the form of a cluster of eggs (ova) of a rare species, in many instances the larvæ are to be obtained with comparative ease, while the perfect insects of the same species are not often seen or not easily captured, and many a rare pupa has been dug out of its hiding place during a season when the entomologist had but little other work to occupy his time.

These and other similar subjects we shall now consider in turn.

Collecting Ova

The collection of ova may be carried on more or less throughout the year. A number of moths are out in February, and even in January if the weather is mild. These soon lay their eggs, which are hatched about the time that the buds of the food plant are breaking. From this time till late in the summer the ova of various species are being deposited, the average period from laying to hatching being from two to three weeks. Then, during the autumn, when the leaves of food plants are turning brown and crisp, ova are still being laid, but these remain unchanged till the new buds of the following spring are bursting.

Of course if you intend searching for the ova of particular species you must previously ascertain the favourite haunts of those species, become acquainted with their food plants, and also with the season or seasons during which the eggs are laid. But the few following hints will suffice as general instructions for the search.

In nearly all cases we must expect to find ova on the food plants of the respective species, but at times, especially with certain moths, we may come across them in the most unlikely spots. Thus, it sometimes happens that a moth settles on a street lamp, and lays her eggs on the framework round the glass, or even on the glass itself. The same thing may take place on the sash or glass of a brightly lighted window.

Such occurrences, however, we must regard as accidental and comparatively rare, and therefore we confine our searchings for ova to the food plants of the species we require.

As a rule the under sides of the leaves will yield the most, but we have already noticed (page 18) that some moths leave their eggs exposed on the upper surface. Again, some larvæ feed on flowers and seeds and fruit, and the eggs of such are deposited on these parts. Those insects which feed on the leaves of shrubs and trees often lay their eggs on trunks, branches and twigs. Sometimes these are laid singly, sometimes in dense clusters; and it is not unusual to find them arranged in rings or spirals with great regularity. When examining the trunks of trees for ova it is necessary to look well into the crevices of the bark, for some insects take particular care to lay them in deep sheltered chinks; but others take no such precautions, and deposit them on exposed ridges or plain surfaces where they are easily discovered.

One difficulty of the ova collector lies in the fact that many insects lay on the upper branches of large trees. Of course a search for these is out of the question; but in places where the trees have been cut down a few years previously, and where a consequent undergrowth has developed, there are considerable chances of success with these species. Young saplings of trees often yield well, especially in places where tall trees of the same species are absent. It may be mentioned, too, that some moths (page 294) actually lay their eggs beneath the surface of water, depositing them on the under surfaces of floating pond weeds; and others (page 298) even enter the nests of wasps and bees for the same purpose. It is clear, then, from these few remarks, that the work of an ambitious collector of insects' eggs is by no means a monotonous task; for his employment takes him into the meadows and woods, leads him to the banks of ponds, and even compels him to tear down banks and hedges for the nests of Hymenoptera at the risk of a sting or two.

One of the most productive sources of eggs is undoubtedly the possession of captured females. When you are out netting butterflies you often see a female that is evidently engaged in her matronly duties. Instead of seeking food from the various flowers in her path, she pays attention only to the foliage, looking out a suitable leaf on which to deposit her eggs. Should you meet with an insect thus engaged which you would like to rear at home, or of which you would like to know the egg, secure it in a perforated pill box with a leaf of the proper plant; and it will often supply you with abundance of eggs for your purpose, in many cases depositing them in the box before you arrive home. The eggs of numerous species of moths are also to be easily obtained from captured females.

Some insects do not seem inclined to deposit their eggs in captivity as freely as when at large, and in order to induce them to do so we must, as far as possible, put them in their natural conditions. Let them have plenty of room, and supply them with fresh twigs of their food plants, kept green by standing them in vessels of water. It is also advisable, supposing you are not well acquainted with the dispositions of the species you have, to keep a portion of the box well shaded from direct sunlight, and allow another part to be as bright as possible; for some species will not lay in a bright light, while others will not do so without it.

Again, while some deposit their eggs within a few hours of quitting the pupa case, others do not lay for several days. With regard to the latter, it is frequently necessary to feed them while in captivity, by placing in the box a piece of rag or sponge that has been dipped in honey or syrup.

Each batch of ova should be carefully examined with a view to knowing them by sight on a future occasion. A sketch should be made in your note book, showing every detail that you can make out with the aid of a good lens. Then observations concerning the season, colour of the eggs, the situation in which deposited, arrangement, and any other useful particulars, should be entered.

In the next chapter some hints will be given concerning the management of ova and the rearing of the larvæ from the time of hatching.

Collecting Larvæ

This occupation is generally far more productive to the entomologist than searching for ova. The latter are very small, usually well concealed, and to be detected only by a careful scrutinising use of the eyes; but the superior size of the larvæ, the frequent bright colouring, and the fact that they are easily beaten from their hold, render the searchings of their hunters comparatively easy and fruitful.

Before setting out on a larva-hunting expedition, there are a few requisites to prepare. These include not only the implements for your work in the field, but also the cages in which you intend to rear your little captives. The latter are described a little later on under the head 'Rearing Lepidoptera,' and the former we will now briefly summarise.

The outfit must consist of a quantity of suitable boxes, a stout hooked stick, a strong net, and a white material to place under the herbage while you are 'beating.'

'Larva boxes' are usually made of zinc, and have little sliding doors in the lids, so that the lids need not be removed while out of doors after the fragment of the required food plant has been inserted. Such boxes are not by any means essential. Small tin boxes will answer all purposes nearly as well, providing a number of small holes be made in them for the admission of air. Chip boxes are also fairly satisfactory, but these also should be perforated. The best way to do this is to push a red-hot iron wire through the chip, making about half a dozen small holes in each box. This method will give you clean holes of a uniform size without otherwise injuring the boxes.

Metal boxes possess the advantage that they keep the food plants moist for a long time, while chip boxes allow them to dry rather rapidly. Yet there are some larvæ that do far better in the latter, since such a quantity of moisture exudes through their skins that they soon become uncomfortably wet if their apartment is not well ventilated. Under these circumstances perhaps it is better to take a supply of both, so that changes may be made as found necessary.

One grave objection to chip boxes, however, is the weakness of the material. They are easily crushed by pressure, and a bottom or a top disc of wood often falls out; but this is easily overcome by gluing narrow strips of calico round the top and bottom edges. Chip boxes should always be treated in this way, and they will then last five or six times as long.

Your supply of boxes should always include one large one of metal in which to bring home a supply of food for the larvæ. If you have a botanist's vasculum, by all means take it, for nothing can serve this purpose better. If not, any rather large square tin box will do, and this may be carried in your satchel, or a couple of hooks may be soldered to it so that a leather strap can be fixed for slinging it over your shoulder.

The net required is that commonly known as the 'sweep net.' It must be very strong, for it has to submit to rather rough usage. The frame must be made of thick wire; and the bag, which need not be more than a foot deep, should be of strong calico or holland.

Now with regard to the white material previously mentioned. This may be a square of calico, hemmed round the edges. Nothing is more convenient than this, as it occupies but little room in the pocket when not in use, if neatly folded. The material need not be thick, but the larger it is the better. Many prefer a white umbrella or an ordinary umbrella with a white lining, but as this is only a matter of taste and convenience you must decide for yourself as to which you will use.

If your field of operations is only a little way from your head quarters, and quantity of luggage therefore not a serious consideration, you may provide yourself with a heavy mallet, loaded if necessary with a pound or two of lead. This will prove very useful in shaking larvæ from trees and large branches. Lastly, take a pencil and a note book or writing paper for your observations in the field.

Now for the choice of the season. Larvæ are to be found all the year round. Early in the spring, as soon as the buds are bursting, some break out of the eggs recently laid by the moths that appear in February and March. Later on, during April and May, a host of both butterflies and moths are busy arranging for their broods. Then, throughout the whole of the summer, thousands of caterpillars of all sorts and sizes are to be met with everywhere. And finally, during the bleak winter months, you may amuse yourself by digging the hybernators out of their hiding places where they rest themselves till the spring sun again calls them out to refresh them with the young and tender leaves of a new year. Thus, unless you are merely intending to search out certain species you happen to require, there is not much difficulty in settling on the season.

The day selected should be dry, for your work lies among the herbage of banks, meadows, and woods, and nothing is more unpleasant than wading through a wet and dense vegetation, or beating down on yourself a shower of large drops from the branches of trees and shrubs.

Having reached the hunting ground, the first thing to do is to look out for signs of the presence of larvæ rather than for the larvæ themselves. Healthy vegetation with sound leaves must be passed by as untenanted; but the presence of partly eaten foliage immediately arouses suspicion.

A little experience will soon enable you to distinguish between the ravages of larvæ and of slugs, snails, wasps, &c. Some of the smaller larvæ certainly eat out clean holes like those cut by Hymenopterous insects, but as a rule they bite away at the edges, leaving the midrib and the larger veins standing out almost naked.

By looking well into the edges of the eaten leaves, it is easy to see whether the marauders have been recently at work. If they are dried up and discoloured, it is not of much use to search; but if still green and moist, you may feel almost sure that the hungry larvæ are not far off.

In this case you will carefully turn over the leaves to examine the under sides, and also the leaf stalks and branches or stems; but you must be prepared for all kinds of protective mimicry. Little green caterpillars will be seen lying on the midrib or veins, so straight and so still that they are scarcely perceptible. Others are snugly tucked in a depression of a leaf with the same result. Then we must also be prepared for the artful little tricks of the larvæ of Geometræ (p. 268), by which they imitate stalks and twigs so closely that a sharp eye is necessary to discriminate between the two.

While thus searching we may meet with the cast skin of a caterpillar. This gives us fresh hopes, and so we continue our careful examination. At last, on grasping a leaf in order to turn it over for inspection, we feel something hairy or something soft and smooth. But lo! it is gone. It is one of those numerous caterpillars that feign death and drop to the ground on the slightest sign of danger. We search below for it, but the density of the vegetation renders this hopeless, and we are just about to start off in search of a more productive locality when we espy a quantity of the excrement of larvæ lying on a little bare patch of ground close by. This gives us a new idea. Here is another indication of the presence of the creatures we require, one that we can put into practice; and by-and-by we learn that in many cases this is really the surest sign of their whereabouts.

We look at these little pellets of excrement, and gain at once some idea of the size of the larvæ that produce them. Then we observe whether they are fresh and moist, or dry and stale. If the latter, it is not of much use to examine the leaves above; but if otherwise, there is little doubt of our meeting with larvæ, as the present position they occupy is so truly marked. The leaves just over them are carefully examined, either by turning them over as before described, or, if the height of the foliage admits of it, by placing our heads below and looking upward.

If we find that the larvæ are some of those that endeavour to escape by feigning death and allowing themselves to drop at the slightest disturbance, the net is always kept beneath the leaves we are touching in order to intercept them in their downward journey.

Continuing the search, we meet with leaves that are rolled up and bound with silk threads, and others that are drawn together and similarly bound. These are carefully uncurled and pulled asunder with the result that active little larvæ are exposed to view, or, it may be, pupæ are discovered. In some cases flowers are drawn together in just the same way, and an examination reveals one or more of the species that prefer petals and other parts of flowers to the green leaves.

Silken threads always arouse our suspicions. These may be seen lying on the surfaces of leaves, and passing from one leaf to another, or they may be hanging perpendicularly from the branches of trees above. In the latter case a larva may be frequently seen on the lower extremity of the fibre, swinging gently in the breeze, and, should we require it, we have only to place the open box below for its reception.

Hawthorn and other trees are sometimes seen almost devoid of leaves, nearly every bit of green having been greedily devoured by a host of small larvæ. In such cases we often meet with dense clusters of silk fibres that may easily be mistaken for spiders' nests. But when we look more closely into the structure we observe that we have discovered instead nests of gregarious larvæ, such a large number being in each little community that the deplorable appearance of the tree is at once explained.

A little farther on we meet with a sickly-looking plant in the midst of a number of flourishing individuals of the same species, and stop to make inquiries into the cause of this strange occurrence. Is it due to a poorness of the soil? No, this cannot be the case; for intermingled with its roots are those of its flourishing companions. We pluck a stunted and half-shrivelled leaf and examine it. At first we do not notice the cause of its peculiar condition; but, holding it up to the light, and looking through it, we see a number of little galleries that have been eaten out of its internal soft substance, leaving the thin skin (epidermis) almost entirely intact. But nothing more is to be seen. Another leaf is examined in exactly the same way; and here we see the little destroyer, lying motionless in its burrow till a gentle pressure applied against it from outside causes it to wriggle along its narrow passage. This is the larva of one of the little leaf miners mentioned again on page 303.

Reaching a little marshy spot we see a number of water-loving reeds, most of them beautifully green and in a flourishing condition, but here and there in their midst is a poor stunted specimen—another result of the ravages of the larvæ of one or more moths. An examination of the blades reveals nothing; but on splitting open the stalk we discover some larvæ that have already devoured a quantity of the internal pith, and thus endangered the life of the plant. On inspecting other similar reeds we are at first puzzled as to how the larvæ could get inside the stems without damaging the outer portion; but at last we see in each one a little discoloured hole that was eaten out by the young caterpillar just after its escape from the egg. Once within the reed, it found a plentiful supply of food, and there grew at the expense of the plant without doing any further external damage save by causing a stunted growth.

It may be that the stem eaters we have found are just about full grown. If so we examine a number of the stems with a hope that we may find one or two that are just about to change to the chrysalis state, or even a pupa already formed. By this means we may secure one of the perfect insects without the necessity of feeding larvæ at home. Such a consideration becomes a most important one when it happens that the required food plant is one that cannot be easily obtained.

Close by the reeds is another water-loving plant in the form of an old willow tree. This is always an attractive object to the entomologist, so it comes in for a share of our inspection. On its leaves we may find several species of the larvæ of Lepidoptera, including those of some of our largest insects. But a strange feature catches our eyes as we happen to glance at the bark of the tree. Here we see a few holes of different sizes, about which are a number of little fragments of wood that remind us of 'sawdust;' and, examining the ground below, we see quite a little heap of this dust, looking just as if a carpenter had been at work on the spot.

This is not the effect of a saw, however; it is a sure sign of the ravages of wood-eating larvæ (p. 224), whose powerful jaws gain them admittance into the very hearts of trees, and the application of the nose to one of the larger holes leaves no doubt of the presence of the large and beautiful caterpillar of the Goat Moth (p. 224).

If we require any of these wood-eaters, either for rearing or for preservation, we must be prepared for a little rather heavy work. A strong pocket knife is not sufficient, but with a good chisel the wood can be gradually cut away, and the galleries traced, till at last we come to the larvæ snugly resting in their burrows.

It often happens that the tree thus tenanted is half decayed, and consequently the work is rendered much easier. Also, while tearing away the wood, we often meet with a number of cocoons that have been constructed by the caterpillars for their winter quarters, or as a resting place while undergoing their transformations. These are composed of the wood dust bound together by strong silk fibres, and are often in such a good state of preservation that they form useful illustrations for the cabinet.

As further aids to larvæ searching we may mention that many species—chiefly of the Noctuæ—hide under the surface of the ground or among dense and low herbage during the day, and come out to feed only by night; that many others feed on roots, and are therefore seldom seen above the surface of the soil; also that a good number burrow into fruits, in the interior of which they spend the whole of their larval stage. The best way to secure the latter is to examine the 'windfalls' that lie scattered on orchard lands, for it is a well-known fact that the fruits that are infested with larvæ generally fall earlier than others—a result that must be attributed to the damaging work of the larvæ themselves.

All the larvæ collected should be carefully boxed at once, a separate compartment being used for each species, and a few fragments of the food plant being introduced in each case. It is also a good plan to have each box previously lined with moss as a further addition to the comfort of the captives. Without such a precaution some of the more delicate species are liable to injury during their transmission from field to home.

Hitherto we have obtained our larvæ by searching only, but there are times and occasions when our boxes may be far more rapidly filled by methods that are not such a tax on our time and patience. Suppose, for instance, that we reach a bush, the mutilated leaves of which seem to show that larvæ are present on its branches. We spread our white cloth or open out the white-lined umbrella just under a selected branch, and then tap that branch very smartly with our stick.

Down comes a host of living creatures! Spiders, larvæ, beetles, aphides, earwigs, and what not, struggling and running about on our white fabric in all directions, and all mingled with bits of stick, leaves, and fragments of all kinds. We leave the cloth or the umbrella, as the case may be, quite still for a few seconds to allow all the living creatures to get a good foothold, and then, raising it into a vertical position, allow all the rubbish to drop off.

We can now put the cloth down again, and select as many of the larvæ as we require, giving our first attention to the nimble runners and loopers that are already near the edge and just on the point of making their escape. This productive method of larva hunting is known as 'beating,' and is particularly applicable to tall herbs and the lower branches of trees and shrubs.

The same principle may be employed in the case of branches that are quite out of the reach of the stick, but the blows are here applied to the trunk, a mallet or some other rather heavy implement taking the place of the stick.

Another splendid method of securing larvæ where mere searching would be tedious and unproductive, lies in the use of the sweep net described on page 102. This implement comes into service in waste places that are covered with rank vegetation, in clover and hayfields, and in all spots covered with low herbs.

Walking among the vegetation, the net is swept right and left before you, and the contents examined at frequent intervals. It is advisable to work the different species of herbs separately as far as possible, otherwise there may be some difficulty in the determination of the food plants of the mixed larvæ that the net will contain. If, however, this plan is impracticable, you may save time by turning out all the 'sweepings' into one large box, leaving the sorting to be done at home in leisure hours.

Collecting Pupæ

We have seen that ova and larvæ may be obtained in greater or less abundance at all times of the year, so variable are the seasons of the different butterflies and moths. The same remark applies equally well to pupæ; but so many of the Lepidoptera spend the winter months in the chrysalis state that this period may be regarded as the harvest time of the pupa hunter.

A large number of caterpillars undergo their change to the quiescent state during the months of August and September, and, of course, remain in this state until the warm days of the following spring or summer. And as insects even in the pupal stage have a number of enemies and dangers to contend with, it is advisable to start your search for them as soon as possible after they have changed.

If you set your mind on searching for particular species, you should endeavour to ascertain the usual time at which such species pupate; make any necessary allowances for the forwardness or backwardness of the season, and then allow a week or two for the change to be completed, for insects should never be disturbed at times when their metamorphoses are in progress.

For general pupa hunting the best season is undoubtedly from the end of August to the end of October, but there is no reason why the work should not be carried on throughout the winter. If, however, you continue your work so late, you must not expect nearly as much success as time advances. You must remember that entomologists are not the only pupa hunters. Many hungry birds are always on the look-out for insects, and seem to enjoy them equally well in all their stages. Those that hybernate on or under the ground are liable to fall a prey to moles and beetles. In addition to these dangers, all pupæ are subject to the effects of extreme cold, dampness, or floods.

As regards the choice of a day, very little need be said. Any day that is sufficiently genial for yourself will do for your work, except that periods of hard frost render the ground too hard for digging—the most profitable part of the pupa hunter's task.

The apparatus required is extremely simple: A satchel or large pockets full of small metal or chip boxes, a small garden trowel, and a strong chisel.

If metal boxes are used they should be perforated; in fact, nothing is better than the ordinary larva boxes of the dealers. All the boxes, of whatever kind, should be lined with moss previous to starting work.

The trowel and chisel do not pack well with a number of small boxes, therefore it is a good plan to fix them in a couple of leather sheaths attached to your belt. In this position they are far more handy for use, and the boxes are also in less danger of being crushed or damaged, as they probably would be if in contact with hard and heavy tools.

A note book is also a valuable addition to your outfit, as it enables you to make memoranda concerning the trees and localities from which you obtain your pupæ.

The best localities for pupa hunting are clearings in woods, parks with numerous large timber trees, and meadows in which large isolated trees are scattered; and the best trees include willows, poplars, oaks, beeches, birches, elms, and hawthorns.

The best thing you can do on arriving at the selected hunting ground is to make at once for isolated trees of large size, and work each one as follows:

First examine well the crevices of the bark, for many caterpillars descend the tree to within a short distance of the ground, and then seek out a snug little crevice in which to spend the winter, often protecting themselves with silken cocoons, or constructing a neat little shelter of gnawed fragments of the wood cemented together.

If there is any loose bark, very carefully force it out with your chisel, and examine both its inner surface and the wood from which it was removed. The wood thus exposed may reveal openings of the galleries of wood-eating larvæ, in which case, unless the material is too hard to be broken up with the chisel, you may be able to trace out a few pupæ. Where these exist, they are usually to be found very near the entrance, sometimes even protruding slightly from the opening, for the larvæ generally place themselves in this position of easy escape when about to change.

Next give your attention to the moss, if any, covering the lower portion of the trunk. This affords a very favourite shelter to many species. Tear it off very carefully, beginning at the top, and watch for loose pupæ and cocoons as you do so. Then hold the clumps you have removed over a patch of bare ground or over a spread handkerchief, and pull it to pieces, in order that any pupæ it contains may fall out; also examine the fragments carefully for others that may remain attached.

This done, the surface of the ground must be examined. Remove all dead leaves, and watch for pupæ that may be sheltered beneath them. If any loose stones lie on the ground, turn them over. Search well into the angles between the roots, and if there are any holes or hollows beneath them or in the trunk itself, pull out all loose matter within, and feel gently above and around for cocoons.

After all loose matter has been removed, there still remains the soil for examination. If this is very hard and clayey, it is probably useless to carry the search any farther; also if very wet you need not expect much; but if comparatively dry and friable there are more hopes of success.

As a general rule the north and east sides of the trunk are drier than those which are exposed to the heavy rains brought by the south and south-west winds, and are consequently more favoured by larvæ that are seeking a resting place for the winter.

Most larvæ seek shelter in the angles between the roots of the trees on which they fed, but a few species seem to prefer the edges rather than the corners; and in cases where no such angles are formed at the surface, you will do well to examine the earth and turf all round the trunk; but it is generally useless to extend the search more than a few inches from the tree.

After having searched every available nook and corner as far as possible without digging, thrust the trowel obliquely into the soil a few inches from the tree, turn over the sod, and then examine the spot from which it was removed. Now give your attention to the sod itself. If loose and friable, break it up gently, keeping a sharp eye for falling pupæ, and also for earthen cocoons that are easily mistaken for little lumps of soil.

If the soil is held together by roots, it must be pulled to pieces, and the fragments shaken over a bare piece of ground where the fall of a pupa or cocoon could be easily seen; and if you have removed a grassy turf, it will be necessary to look between the bases of the blades as well as among the roots.

In this way you may search round tree after tree, wherever the soil is of such a character as to allow of the admittance and shelter of larvæ. But the variability of your success will be quite beyond your comprehension. Sometimes you will sight a grand old oak with the most favourable anticipations, and consider yourself quite certain of a good find when you discover, on a nearer approach, the liberal coating of moss that clothes its trunk and the dry sandy soil at its foot; and yet the most careful search ends in nothing but disappointment. At other times you try your luck at tree after tree without ever seeing a single pupa or even a cast-off case, and then, when just on the point of despairing, you search round another that is apparently much less promising, and, to your great surprise and delight, a dozen or two are turned out in a few minutes. Such an occurrence as this is not at all uncommon, and cannot be satisfactorily explained, but we must take things as they come and make the best of them, remembering that pupa searching is one of the best of all entomological operations wherewith to test one's perseverance and patience.

It may be mentioned, in conclusion, that the pupæ of Lepidoptera are never to be found far below the surface of the soil. Generally they exist, if buried at all, only an inch or two down, and very rarely at a greater depth than four inches.

In our next chapter we shall learn how to rear the perfect insects from the earlier stages we have been considering.

CHAPTER VIII
REARING LEPIDOPTERA

Management of Ova

In the management of insects in all stages the strictest attention must always be paid to one general rule on which the success of the work almost entirely depends; and that is—keep every specimen as far as possible under the same conditions as those in which you find it in nature.

Applying this principle to ova, we store them in airy and light places, protected from the direct rays of the sun, and avoid handling and rough treatment of any kind. It is also advisable in most cases to maintain a slight amount of dampness corresponding with that of the open air at the particular season of the year.

They do not require much space, and it is certainly desirable not to give much, otherwise the newly hatched larvæ, when their time arrives, will actively wander all round their premises in search of food, and give you no end of trouble in gathering them up.

Chip boxes are, as a rule, very good and very convenient receptacles for ova. After placing the eggs in these, cover them over with very fine muslin, held in place by elastic bands; and label each as far as you can with the name of the species contained, and other particulars worth remembering. The boxes may then be put in front of a window facing north, or in any situation within or out of doors where rain and sun cannot reach them. A greenhouse is an admirable place in which to keep them, the natural dampness of the atmosphere being apparently a considerable assistance to the tiny larvæ just as they are striving to escape from their shell.

Whatever place is selected, it is absolutely necessary that the ova be carefully watched, so that each brood may be supplied with the required food plant within a few hours of quitting the shells.

When ova are kept in a warm room, very great inconvenience and even loss is sometimes caused by the appearance of larvæ before the necessary food plant shows its buds. Yet, on the other hand, it is sometimes a great gain to the entomologist to get certain broods off early in the season, providing the food is at hand; for in this way he can not only get some of his work over during a slack season, but also, if he desires it, secure an additional brood; that is, one brood more than the usual number. Thus, supposing a certain species he is rearing is naturally double-brooded, he can, by judicious management, secure three successive broods before the food plant casts its last leaves.

This hastening of the natural events of insect life is known as forcing, and merely consists in subjecting the species concerned to a reasonable amount of artificial heat, such as that of a room in which a fire is always kept, or of a hothouse.

It is interesting at all times to note the dates on which eggs are laid or collected, and the times at which the young larvæ appear. In addition to this all changes that take place in the colours or forms of eggs should be carefully observed; for such changes will assist you in distinguishing between fertile and sterile ova, and also enable you to judge approximately as to the date of the appearance of future broods.

Rearing Larvæ

The main point in connection with the rearing of larvæ is certainly the selection and construction of the cages or their substitutes. For newly hatched and all very small caterpillars a small bottle with a wide mouth makes a very fair abode. Put a layer of sand or sifted soil in the bottom, fix in this a small twig of the food plant or lay a few leaves on the top, and then, after the larvæ have been introduced, cover the top with a piece of muslin, held in place by an elastic band.

The great drawback with this arrangement is the lack of any provision for keeping the food moist and fresh, thus rendering a change necessary at very frequent intervals; but this may be obviated by using damp sand as a foundation for the little twig of food plant. With this improvement, if you cover the top of the bottle with apiece of glass, a saucer, or any impermeable substance, you may keep the twig fresh for several days, generally until the disappearance of the last leaf calls for a fresh supply; but it is very doubtful whether the damp atmosphere resulting from this inclosure is not injurious to the larvæ. It certainly does not seem to have much influence on some, but the unhealthy conditions that result must be detrimental to the inmates. It must also be remembered that many species require a dry soil in which to burrow when about to change.

When the time comes for the change of food, great care must be taken not to injure young and small larvæ. In many cases they need never be touched, for if a fresh twig be placed beside the stale one, they will readily find their way to it; and to facilitate this, and also to afford a convenient foothold to those larvæ that accidentally fall from the twig, the layer of sand at the bottom of the bottle should be covered with moss or cocoa-nut fibre.