ORDER NEUROPTERA.
Including the Dragon Flies, Lacewing Flies, Day Flies,
Stone Flies, Caddis Flies, and their Allies.
Next to the butterflies and moths, the Neuroptera (or nerve-winged insects), to which belong the Dragon Flies, Lacewing Flies, Day Flies, Stone Flies, Caddis Flies, and their allies, are undoubtedly the most beautiful members of the insect tribe. Though they cannot compete with the Lepidoptera in point of colouring, it is questionable whether they are not more graceful and elegant in appearance.
The order Neuroptera was founded by the great Swedish naturalist Linnæus, and its name has been kept intact since, though the classification of the insects comprised in it has undergone many modifications.
The Neuroptera are not a very numerous body of insects compared with either the Coleoptera or Lepidoptera, but they contain some of the largest and most handsome insects known. The order is very well represented in the temperate zones, though the finest species are met with in the tropical parts of the world. Nearly 700 species are known to inhabit the British Isles. In the whole world their number may be given in round figures at about 4,000, but there is no doubt that this number may be considerably increased.
The largest and most handsome species are the Dragon Flies or Ornoptera, one species occurring in our own country, measuring fully four inches in expanse of the wings. The Lacewing Flies (Hemerobiidæ), the Day Flies (Ephemeridæ), the Stone Flies (Perlidæ), and the Caddis Flies (Trichoptera), are among the other more conspicuous members of the group.
The Neuroptera may be divided into three great sub-divisions, according to certain well-defined characteristics. The modern tendency is to raise each of these sub-divisions to the rank of orders.
The Neuroptera may be classified as follows:—
Sub-Order 1, Planipennia, or true Neuroptera.
Metamorphoses complete, larvæ, mostly terrestrial.
Sub-Order 2, Trichoptera, or hairy-winged Neuroptera.
Metamorphoses complete, larvæ aquatic. Wings of Imago clothed with hairs.
Sub-Order 3, Pseudo-Neuroptera, or false Neuroptera.
Metamorphoses incomplete.
The most important distinction between the first two groups and the third is that the former undergo complete metamorphoses, whereas in the latter the transformations are incomplete or imperfect. The latter for this reason are often classified as a separate order.
The Trichoptera are also placed by some entomologists in a distinct order, on account of the peculiarity in their wings being clothed with hairs. They, however, present so many points both in habits and structure, analogous with the true Neuroptera, that we have retained them as a sub-division of the Order.
TABULAR VIEW
OF THE
PRINCIPAL FAMILIES OF THE NEUROPTERA.
Sub-Order 1.—Planipennia.
The Planipennia contains the most typical forms of the Neuroptera. This sub-order is subdivided into six families, four only of which contain representatives in the British Isles. They are most abundant in the tropical parts of the world, where also the most handsome and curious forms occur.
Family 1, Myrmeleontidæ.—The Ant Lions are the most familiar and important members of this family. The common Ant Lion (Myrmeleon europæus), which is abundant in sandy places in the south of Europe, is a slender and elegant creature, with large finely reticulated rings. The larva, to which the name of "Ant Lion" properly belongs, is of a stout form and a greyish-yellow colour, covered with warty processes and with hairs. Its food consists of ants and other small insects, which it captures by a singularly ingenious arrangement, namely, by means of a funnel-shaped pitfall which it constructs in the sand, and at the bottom of which it lies. When any unfortunate insect ventures too near, the Ant Lion sends up a shower of sand, and the victim in its consternation falls down the pit, where it is speedily seized and devoured.
Other species of ant lions are known to occur on the continent of Europe, but none hitherto have been discovered to inhabit this country.
Family 2, Hemerobiidæ.—The second sub-family contains the Lacewing Flies, many representatives of which occur in the British Isles. They are among the most elegant and beautiful of the Neuroptera.
The Golden-eyed Fly (Chrysopa vulgaris) is a very abundant and well-known example, but notwithstanding its great beauty it is capable of emitting a very disagreeable odour when handled. This is a delicate green insect with a body half an inch long, and which may be seen almost everywhere on warm summer evenings, flying slowly about from tree to tree. The eggs, which are little round or oval bodies like small pearls, are deposited by the female in groups upon the leaves of plants and trees. The larva when fullfed is about half an inch in length. The food consists of plant lice and aphides, and it is thus a very beneficial creature, and should be encouraged by every gardener. The pupa of this insect is enclosed in a cocoon. Between thirty and forty species of lacewing flies are known to occur in our own country.
Family 3, Mantispidæ.—This family contains only one genus—viz., Mantispa, or the Mantis Flies. A single species, Mantispa pagana, is common in southern Europe, but does not occur in the British Isles.
Family 4, Sialidæ.—In the fourth family of the Planipennia the larvæ are aquatic in their habits with very few exceptions. The pupa is not enclosed in a cocoon as it is in the Hemerobiidæ. The single common British species (Sialis lutaria) is a blackish-brown insect, rather more than half an inch in length. It is well known to anglers, and may be found abundantly in the spring and early part of the summer upon walls and palings in the neighbourhood of water, and upon the stems and leaves of grasses and other plants growing in the water or upon its bank.
In repose the wings of this insect, as in the Hemerolicidæ, are laid over the back. They are sluggish creatures, and do not readily take to flight.
Family 5, Raphiidæ.—This family contains the curious group of insects called "Snake Flies" or "Camel Flies," which are included by some entomologists in the previous family. They have characteristics, however, which entitle them to be placed apart. They have a rather large head, which is attached to a greatly elongated prothorax by a thinnish neck, so that the head has considerable freedom of motion. The species are not numerous, four kinds only occurring in Britain. The larvæ reside under the bark of trees, where they feed upon minute insects. The commonest species is probably Raphidia megacephala.
Family 6, Panorpidæ.—The Panorpidæ, or Scorpion Flies, are very curious creatures, characterised above all things by the perpendicularly placed and greatly elongated head.
The larvæ, so far as they are known, live in the earth, and are like caterpillars in their general form.
Five species occur in this country, the best known being Panorpa communis, which may be met with almost everywhere about hedge banks and in lanes. It is about half an inch long. The wings are transparent, with dark brown spots, which are more or less confluent.
Another species, Boreus hiemalis, which possesses no wings, is found on the ground among leaves in the winter time. It does not exceed one-sixth of an inch in length, and is of a metallic-green colour.
Sub-Order 2.—Trichoptera.
The members of this group are the insects commonly known as Caddis Flies, and they are often ranked as a separate order by entomological writers.
Nearly 600 species of Trichoptera occur in Europe, of which about half the number are indigenous to the British Isles. The larvæ are aquatic, and when full-grown prepare for themselves curious dwellings composed of sticks, stones, and other materials wherein to pass the pupa state. They may be seen almost everywhere where there is water.
The caddis flies may be divided into two families, though the distinguishing marks are so minute that they really ought to be classified as one family only. To Mr. McLachlan we owe many thanks for his researches in this group of insects.
Family 1, Inæguipalpia.—This family includes the largest species of the tribe, and are principally found in northern regions.
One of our largest British species is Phryganea grandis, which measures four-fifths of an inch in length, and over two inches in expanse of the wing. It is an abundant insect, of a brown colour, with yellow rings on its antennæ, and the anterior wings are ash-coloured, clothed with brown.
The larvæ of this group for the most part inhabit quiet waters, ponds, canals, etc.
This family is subdivided into three sub-families, viz., Phryganeidæ, Limnophilidæ, Sericostomidæ.
Family 2, Æguipalpia.—This family constitutes a second group, and also contains many species, many of them, however, being very minute insects, some hardly one-eighth of an inch across the wings. They make little cases of silk resembling seeds, to the outer surface of which they attach grains of sand, etc.
The Æguipalpia contains four sub-families—viz., Leptoceridæ, Hydropsychidæ, Rhyacophilidæ, and Hydroptilidæ.
Of the Leptoceridæ, Molanna augustata may be taken as a typical example, the larva of which lives on the sandy bottom of pools, and is very difficult to detect.
Sub-Order 3.—Pseudo-neuroptera.
In the third sub-order of the Neuroptera are grouped together a series of insects which present great divergences of character, and really do not belong to the true Neuroptera on account of their incomplete metamorphoses. They, however, for the most part, resemble the Neuroptera in the structure of their wings.
They are divided into several tribes and many families.
Tribe I.—Ornoptera or Dragon Flies.
To this tribe belong the Dragon Flies, the largest and most beautiful members of the whole order.
About 1,500 species have been described from various parts of the world, and of these about fifty are known to inhabit our own country.
Their habits are very much alike. The insect passes all the earlier stages of its existence in water. The larvæ are most voracious creatures, and are undoubtedly the most predaceous of insects. The apparatus by which they capture their prey consists of a peculiar modification of the labium.
When full grown the larvæ crawl up the stem of some aquatic plant out of the water, and after resting there for a longer or shorter time the skin splits open along the thoracic region, and the perfect insect by degrees struggles out of its investment, and when the wings are dried it starts off to continue the same scene of rapine which has characterised its subterranean existence.
The perfect insect may be seen hawking about for insects in the neighbourhood of pools in all fine weather during the summer and autumn months. In dull weather, however, they usually remain at rest on the leaves of plants and trees, etc. The eyes of Dragon Flies are most beautiful objects when viewed under the microscope; they are composed of a great number of facets or lenses. In one species of Dragon Fly as many as 10,000 of these facets have been counted in each of its eyes.
Besides these compound eyes most dragon flies have additional eyes, called Ocelli, which are situated on the top of the head; they are, however, quite simple.
It is commonly thought by persons who are not naturalists that dragon flies sting; such an erroneous idea we take the opportunity to correct.
The Ornoptera are divided into two principal families.
Family 1, Libellulinæ.—To this family belong all the great dragon flies, mostly thick-bodied insects. It is subdivided into four sub-families.
To the first sub-family, the Libellulidæ, many common and familiar dragon flies belong. The best known is what is vulgarly called the "Horse-stinger" (Libellula depressa), an insect about two inches long, with a rather depressed abdomen, which is yellowish-brown, with yellow spots on the sides in the female, and coated with a beautiful violet-blue powder in the male.
It may be seen almost everywhere, hawking for flies about rivers and ponds, during warm weather.
The second sub-family, the Cordulidæ, contains four British species, of which the beautiful Cordulia metallica is the typical example.
The Æschnidæ contain some of the largest members found. The great dragon fly (Æschna grandis) is one of these. It is nearly three inches long and four inches in expanse of the wings, and is of a light rusty-brown colour with a few pale markings.
Of the Gomphidæ only four species inhabit our own country.
Gomphus vulgatissimus is a black insect, nearly two inches long, with yellow bands on the thorax, and a line of the same colour along the back of the abdomen.
Family 2, Agroninæ.—This family contains a number of slender-bodied insects. There are two sub-families.
The Agrionidæ are a very numerous group. The typical form, Agrion puella, which is a beautiful, slender creature, measures about two or two and a half inches in expanse of the wings. The abdomen of the male is banded with azure blue, that of the female being brassy-black.
The Calopterygidæ contain only two British species—viz., Calopteryx virgo and C. splendens.
Tribe II.—Subulicornia.
The second tribe of the Pseudo-neuroptera contains a group of insects which are so similar to one another in form that they are all included in one family.
Family 3, Ephemeridæ.—The Ephemeridæ, or Day Flies, as they are popularly called, are delicate, elongated, soft-bodied creatures, with a moderately small head. The antennæ, which spring from the forehead below the ocelli, are short and awl-shaped. These insects, which seem to be found mostly in temperate climates, are remarkable for the great delicacy of their structure, and for the extreme shortness of their lives in the perfect state, which seems in general scarcely to exceed a day.
Nearly fifty species of Ephemeridæ occur in this country. The best known is Ephemera vulgata, of which the sub-imago is called the "green drake," and the imago the "grey drake" by anglers. The two-winged Clöen diptera, which, however, is a much smaller species than the foregoing, is also very abundant.
Tribe III.—Plecoptera.
The Plecoptera contain only one family.
Family 4, Perlidæ.—The Perlidæ, or Stone Flies, are chiefly inhabitants of the temperate regions; they are of small size, and not very numerous in species, about thirty being indigenous to the British Isles.
The larvæ, which are aquatic in their habits, closely resemble the perfect insect in form. Their food consists of other insects and they prey especially upon the larvæ of the Day Flies.
The perfect insects are usually found resting quietly on plants and other objects on the banks of streams. The large brown species, Perla bicaudata, appears in the spring, and is very common in the neighbourhood of pools, streams, and canals.
Tribe IV.—Corrodentia.
This tribe contains two families, one of which is represented in the British Isles.
Family 5, Psocidæ.—This is a family of small insects with simple veined wings. They have a rather large head, and bear a pair of long tapering antennæ. They are found upon trunks of trees, old palings, walls, etc. They are very active in their movements, and generally appear in the imago state about the end of summer or beginning of autumn.
Atropos pulsatorius is one of these. It lives in books and among old damp papers, whence it is often called the "Book Louse."
They are also very destructive to collections of preserved insects and plants. About thirty species occur in this country.
Family 6, Embiidæ.—This family contains no representative in the British Isles, and consists of a small number of almost exclusively exotic species. Two species, however, inhabit the continent of Europe, one of which, Embia Solieri, occurs in the south of France on the Mediterranean littoral.
These insects are very closely allied to the Psocidæ in their habits.
Tribe V.—Socialia.
The Socialia contains a very peculiar group of insects closely allied to the cockroaches in the Orthoptera. They may be considered a connecting link between that order and the Neuroptera. There is only one family.
Family 7, Termitiæ.—The Termitiæ, or White Ants, are almost exclusively inhabitants of tropical climates, and are unrepresented in our own country.
They are a very remarkable family of insects. They build most complicated dwellings, consisting of innumerable galleries and chambers, and they are so interesting in their habits that every traveller who has seen anything of them has always a great deal to relate concerning them.
One species, Termes lucifugus, inhabits the south of France, and is very well known on account of the mischief which it sometimes causes.
Tribe VI.—Physopoda, or Thrips.
This tribe of insects, to which the name Thysanoptera is sometimes applied, contains many curious forms.
There are two principal groups of these insects—namely, the Tuberlifera and the Terebrantia. They are generally known to gardeners by the name of "Thrips." Some of them occasionally prove injurious to cultivated plants. This is especially the case with the Corn Thrips (Thrips cerealium), which generally attacks the ears of corn, and, when numerous, is very mischievous.
Tribe VII.—Mallophaga or Bird Lice.
These insects, which are known as "Bird Lice," were formerly placed among the true lice, but they differ in the possession of biting mouths, and in the diet to which such a structure adapts them.
A great number of these curious little insects have been recorded, and they inhabit all parts of the world. They live among the feathers of birds and the hairs of mammalia.
Almost every animal and bird is subject to these parasites.
The common fowl, duck, goose, game birds of all kinds, and pigeons, are very commonly infested by them, as are also the dog, the cat, the sheep, and the guinea-pig.
The two principal families of the Mallophaga are the Philopteridæ and the Liotheidæ.
Tribe VIII.—Thysanura or Bristle Tails.
The forms composed in this tribe of insects are reckoned at present to be the nearest resemblance to the theoretical progenitors of the insects; in fact, Sir John Lubbock hints that they might well be regarded not as insects at all, but rather as the surviving representatives of a group formed by the ancestors of the whole multitude of insect types.
The food of these creatures consists of decayed vegetable matter.
Three principal families may be recognised—viz., Lepesmidæ, Campodeidæ, and Japygidæ.
Tribe IX.—Collembola or Spring Tails.
These insects closely resemble the previous tribe in general character, to which also the same remarks nearly apply.
They are generally small insects, a length of a quarter of an inch being considerably above the average. They are found commonly in loose earth, under decaying leaves in woods, in moss, under the bark of dead trees, and in rotten stumps. They always prefer damp situations.
Cold seems to have but little effect upon them; they will recover their activity after being frozen. One species, Desoria glacialis, is found enjoying itself upon the Swiss glaciers, and another, Degeeria nivalis, occurs upon the surface of snow in many parts of Europe. Some species also may be met with hopping about upon the surface of standing water. Podura aquatica, a minute blue-black species, is common in such situations in England.
The five principal families are the Smynthuridæ, Papyriidæ, Degeeriadæ, Poduridæ, and the Amouridæ.