The Diptera, or two-winged flies, are among the most numerous orders of insects, but they have been so little studied hitherto that we have but a very imperfect knowledge of them, especially as regards the tropical species.
The number recorded in the British Isles is about 3,000, that of the whole world probably exceeds 30,000, and it is certain that this number will be increased immensely as time goes on.
The Diptera may be defined as insects with a sucking mouth (Haustellate), and with only two wings, which are membranous, while the hind wings are represented only by a pair of small knotted organs, called halteres. Their metamorphoses are complete.
The larvæ are footless "grubs," generally with a soft body, but sometimes leathery or even nearly horny. Many of them possess a distinctly marked head, which may contain ocelli, but in the majority the head appears as if it were simply one of the neighbouring segments.
Their food generally consists of decayed animal and vegetable matter, and thus they are very useful as scavengers, particularly in hot climates.
The larvæ frequently live in the substance upon which they feed, while others reside in water, and many are parasitic.
For the classification of the Diptera we owe much to that eminent entomologist, Osten-Sacken, whose arrangement has been here generally adopted.
TABULAR VIEW
OF THE
PRINCIPAL FAMILIES OF THE DIPTERA.
The number of families comprised in the Diptera is so great that space will only permit us to deal very briefly with each.
This tribe contains many well-known insects—namely, the Midges, Gnats, Daddy-longlegs, etc., which are divided into twelve families.
Family 1, Cecidomyiidæ.—These are small delicate species, generally clothed with long hair. They are all vegetable feeders, some of them being very destructive to crops. The Hessian Fly (Cecidomyia destructor) is probably one of the best-known species, on account of the terrible mischief which it has caused in various countries, and particularly in the United States of America. Miss E. A. Ormerod, the well-known economic entomologist, has recently written a great deal concerning this insect, with the view to preventing its increase in our own country.
The Wheat Midge (Diplosis tritici) is another very mischievous species.
Family 2, Mycetophilidæ.—These are generally small species. They are all vegetable feeders. The larvæ live gregariously in fungi, rotten wood, bark, etc.
The Army Worms (Sciara) of America, which belong to this family, sometimes congregate in enormous numbers.
The flies are remarkable for their remarkable powers of leaping.
Family 3, Simuliidæ.—This family includes only one genus, Simulium.
It is, however, widely distributed, and some of the species, which are popularly called Sand Flies, are exceedingly annoying in hot climates.
Family 4, Bibionidæ.—Several species belonging to this group are very familiar insects. Among them is the St. Mark's Fly (Bibio Marci), which is black, with transparent wings in the male and brownish in the female.
These flies appear in the spring, and their larvæ live in dung or damp earth.
Many of the species are popularly called "garden flies."
Family 5, Blephariceridæ.—These flies have long legs, the antennæ are usually long and slender, and the wings broad and long. The type of this family is Blepharicera fasciata, the female of which is a very blood-thirsty creature. It is a dark brown fly, with transparent wings and yellow legs, and it measures about one-third of an inch in length. It is, however, by no means abundant.
Family 6, Culicidæ.—The Culicidæ, or Gnats, are a very extensive family.
The larvæ are nearly all aquatic.
They are generally small, dull-coloured insects, and are often called "Mosquitoes" in the country. These insects frequently cause much annoyance during the summer months to persons engaged in out-door occupations. They are particularly abundant in damp meadows, in the vicinity of water, and also in hay-fields, where the face and hands of the mowers are sometimes blistered to much pain by the suckers of the little creatures.
One of the most troublesome species is probably the House Gnat (Culex ciliaris), which, thirsting for its evening meal, often enters our apartments, sounding its approach by a tolerably loud humming.
Culex annulatus is a little larger, and is said to produce a greater amount of irritation by its bite.
Family 7, Chironomidæ.—These insects are small delicate insects, much resembling gnats in appearance, and are popularly called "Midges." The larvæ of most of the species are aquatic.
The larva of Chironomus plumosus, which is common in stagnant water, is called the "blood worm" from its bright red colour.
Family 8, Orphnephilidæ.—Most of the species belonging to this family are of small size.
The typical species is Orphnephelia testacea, measuring scarcely one-tenth of an inch in length, and is sometimes found in bakehouses. It is of a rusty-yellow colour.
Family 9, Psychodidæ.—This is a small family consisting of minute brown or yellowish species remarkable for their resemblance to moths. They mostly feed on fungi and decayed vegetable substances.
The species of Phlebotomus are troublesome blood-suckers in the south of Europe.
Family 10, Tipulidæ.—The insects belonging to this group are popularly known as Crane Flies and Daddy-longlegs. They are very abundant.
The commonest species, Tipula oleracea, is a grey species with transparent wings, and exceedingly destructive to corn, roots of grass, etc., and no effectual remedy has hitherto been discovered for preventing their attacks.
The familiar Winter Gnat (Trichocera hiemalis) belongs to this family. It may often be seen, even during the dreary months of December and January, dancing to and fro under the shelter of some hedge or wall. In frosty weather it conceals itself beneath the bark of trees, under leaves, etc.
Family 11, Dixidæ.—This family of gnats frequents damp places in woods, and are therefore designated "Wood Gnats." They may occasionally be seen during the summer time in immense swarms.
The species of Dixa are reddish, yellow, or black insects generally of small size.
Family 12, Rhyphidæ.—The larvæ of most of these insects feed upon decayed vegetable matter.
The species of Rhyphus may often be found resting on leaves in damp situations, they may also be seen on windows, and occasionally "dancing in the air."
They are generally brown, yellow, or grey insects of small size.
These insects are generally of much larger size, and more robust in appearance than those contained in the previous tribe. They are divided into twenty-two families.
Family 13, Xylophagidæ.—The Xylophagidæ are thick-looking insects. The head is as broad as the thorax. The legs, which are long and slender, are quite naked. The larvæ live in rotten wood, and the flies may often be seen at rest on the trunks of trees.
Family 14, Cœnomyiidæ.—In this family the head is narrower than the thorax; otherwise they closely resemble the previous family. The typical European species is Cœnomyia ferruginea, which measures about three-quarters of an inch in length, and in colour varies from rusty-yellow to black. The larvæ feed inside the trunks of rotten poplars.
Family 15, Stratiomyiidæ.—These are rather slender flies, varying from half to one inch in length. They are usually found resting on low plants. Many species frequent cow-dung and manure, etc. Several kinds exhibit a metallic coloration, others are black, often more or less varied with white or yellow.
Family 16, Acanthomeridæ.—The Acanthomeridæ are met with principally in America. The typical species, Acanthomera picta, is found in Brazil, and measures more than an inch in length. It used formerly to be largely used in the manufacture of pomade.
Family 17, Tabanidæ.—The Tabanidæ are broad-looking insects. The larvæ usually live in damp earth. The females of these species live on the blood of animals.
The best-known species is the Gad Fly (Tabanus bovinus), which measures more than an inch in length, and is particularly troublesome to cattle in hot weather. It is blackish above, and reddish beneath and on the sides of the abdomen.
The Clegg Fly (Hæmatopota pluvialis) also belongs to this family. It is a dingy-looking insect with mottled-grey wings, and is sometimes very abundant in damp meadows.
Many other species of Tabanidæ, popularly called "Breeze Flies," are plentiful in this country.
Family 18, Leptidæ.—These insects are mostly predatory, though many small species are parasitic on animals and other insects. The larva of Vermilio degeerii lives in sand, and feeds on such insects as fall in its way. Those of the genus Leptis are parasitic on cockchafers and other large beetles.
Family 19, Asilidæ.—The Asilidæ or Hawk Flies are a family of considerable extent, and include many very large and conspicuous insects. They feed on other insects, and are very courageous, sometimes attacking even dragon flies. One of the most common species is Asilus crabroniformis, which is common in the south of England.
Family 20, Midaidæ.—These are large insects resembling the Asilidæ in their habits, and are nearly all tropical. A few species, however, inhabit the south of Europe.
Midas giganteus is found in Brazil and adjacent countries in tropical America. It measures about one inch and a half in length.
Family 21, Nemestrinidæ.—These insects are chiefly inhabitants of tropical climates like the preceding family. They are generally of a black colour, sometimes with red legs. They suck the nectar of flowers through a long proboscis, but nothing is yet known of their transformations.
Family 22, Bombyliidæ.—The Bee Flies belong to this family. They are small or middle-sized insects, densely clothed with hairs. They are exceedingly active insects with long tongues, with which they suck honey from flowers. Their larvæ are often parasitic in their earlier stages on other insects.
They are very useful in North America by keeping down the number of locusts, in the egg capsules of which the larvæ feed.
Two species, Bombyliis major and B. medius, are common in this country, and may often be seen in gardens and open spaces in woods during the spring and summer months.
Family 23, Therevidæ.—This family is a very numerous one, especially those of the typical genus Thereva. They are slender, middle-sized black insects, and their bodies are generally covered with hair. They are generally found in the neighbourhood of bushes and trees.
Family 24, Scenopinidæ.—The Scenopinidæ include a few minute, black flies, not exceeding a quarter of an inch in length. They are not very common, but are sometimes found about windows.
Family 25, Scroceridæ.—This family also contains small species of flies, but their metamorphoses are at present unknown.
They are usually to be found resting easily on dry branches of trees, but are generally rare.
Family 26, Empididæ.—The insects of this group are very similar to the Asilidæ in their carnivorous propensities, but the species are usually of a much smaller size. Empis livida is a common yellowish species measuring about one-third of an inch in length.
Family 27, Dolichopodidæ.—This family is a very extensive one, including a considerable number of genera and species. They are usually small flies often of brilliant metallic colouring. They may be found generally in the neighbourhood of water.
Family 28, Lonchopteridæ.—The species of Lonchopteridæ are small yellowish-brown or greenish flies with lanceolate wings. They frequent the banks of shady streams, and are often found resting on wet stones.
Family 29, Syrphidæ.—The majority of flies belonging to this family are of a moderate size, and possessed of brilliant colours. With the exception of the enormous family Muscidæ, they are one of the largest families of the Diptera.
Most of the species may be recognised at once by their peculiar mode of flight, for they hover motionless in the air, and if alarmed dart off with a rapid motion which the eye cannot follow.
Milesia Crabroniformis is a very large species common in the south of Europe.
About thirty species are found in the British Isles. Of these Syrphus pyrastri is perhaps the best-known example. It is a very wasp-like creature, and is, indeed, mistaken by many people for a wasp. It is a very useful insect, feeding largely on aphides and plant lice, and should therefore be encouraged by every horticulturist.
Family 30, Conopidæ.—The larvæ of most of these insects are parasitic on Orthoptera and Hymenoptera. Many species have a resemblance to wasps in appearance, being striped with yellow and black. The typical genus, Conops, are slender flies measuring half an inch in length.
Family 31, Pipunculidæ.—These are black or brown insects. The head is large and round, generally broader than the thorax. The larvæ are mostly parasitic on other insects. The flies may often be seen in great swarms in shady places in the vicinity of hedges, in lanes, etc.
Family 32, Platypezidæ.—This family contains many beautiful flies. Great numbers of them are marked with orange and silver and black. The larvæ inhabit fungi.
Family 33, Æstridæ.—The Bot Flies are well known on account of the annoyance they cause to cattle. They lay their eggs upon the hides of the animals, and the larvæ, when hatched, make their way under the skin, and there take up their abode, living on the juices of their unfortunate host. It is estimated that the loss occasioned by these troublesome pests amounts to millions of pounds in the British Isles alone. The best-known species is probably Æstrus bovis, which infests the ox. The cattle are so well aware of the danger attending the presence of this insect, that as soon as it appears near them, the whole herd exhibits the most unmistakable signs of terror, rushing about their pasture with their tails in the air, and in case of need taking refuge in water, where the fly will not follow them. Miss E. A. Ormerod has recently paid much attention to the economy of this insect, with the view to finding some remedy for its attacks.
Family 34, Muscidæ.—The Muscidæ is the most numerous family, of the Diptera and it includes many familiar insects. It is divided into two sections, containing thirteen sub-families. The first section, Calypteræ, contains five sub-families. The Tachininæ are parasitic in the larval stage on Lepidoptera. The largest of the Muscidæ found in Europe is Echinomyria grossa, which measures about three-quarters of an inch in length.
Many species of the Dexinæ are of the most metallic-green or blue. They are principally found in Australia.
The Flesh Fly (Sarcophaga carnaria) belongs to the Sarcophaginæ and is one of our largest species. The larvæ of some species are called "Screw Worms" in America.
The fourth sub-family, the Muscinæ, contains the most typical species of the Diptera or two-winged flies. The common House Fly (Musca domestica) is the most familiar example. Several blue-and-green flies are produced from larvæ which feed on more or less putrid flesh, and are well known to anglers as "Gentles." The Blow Fly or Blue Bottle (Musca vomitoria) is one of these, also the Green Bottle Fly (Lucilia Cæsar) which is often common about hedges in the summer time. Many species belong to the sub-family Anthomyiinæ, are very small insects, and their larvæ mine in the leaves of plants like those of Tineæ.
Section 2, namely Acalypteræ, contains eight sub-families.
The species of Scalophaginæ are usually called "Dung-flies." The commonest species, the Yellow Dung Fly (Scatophaga stercoraria), feeds largely on manure and other refuse.
The Ortalinæ are flies of small or moderate size, which are met with principally in woods and fields. The Trypetinæ feed chiefly on fruit. One species, Ceratitis hispanica, is very destructive to oranges in the south of Europe, etc. Of the Piophilinæ, Piophila casei may be taken as the typical example. The larvæ which abound in cheese and bacon are popularly called "Cheese Hoppers," or "Jumpers," in allusion to their habit of springing. The Diopsinæ are principally met with in the tropical parts of the world. They are generally insects of moderate size. Most of the species of Chloropinæ are of small size. Their larvæ generally live in the stems of corn and various kinds of grasses. The Drosophilinæ are small, dull-coloured flies, the larvæ of which feed on fungi, rotten fruit, and similar substances.
The last sub-family, namely, the Agromyzinæ, is very extensive. One of the commonest species is Phytomyza ilicis, the larva of which forms large brown blotches on the leaves of the holly.
Family 35, Phoridæ.—The insects belonging to this family are generally of small or moderate size. They are very active, and may be observed on plants, and also sometimes sunning themselves on windows.
The insects belonging to this section much resemble spiders in appearance. They are all parasitic, and are remarkable for the perfect insect producing its young singly, and that not in the egg state, as in most insects, but either in the pupa state, or as a mature larva ready to become a pupa immediately. This tribe contains only three families.
Family 36, Hippoboscidæ.—The most familiar insects comprised in this family are known as "Forest Flies." The common Forest Fly (Hippobosca equina) is a brown species about one-third of an inch in length, and exceedingly annoying to horses, particularly in the New Forest. The Sheep Tick (Melophagus ovinus) is another well-known example.
Family 37, Nycteribidæ.—These insects are all parasitic on bats, and are commonly known as "Bat Lice." They are wingless, but have a pair of halteres placed upon the dorsal surface.
Family 38, Braulidæ.—This family includes only a single species, which is parasitic upon the honey bee. Its name is Braula cæca, and it is an exceedingly minute creature.
The tribe Aphaniptera was formerly considered to be a separate order, but it is now generally included among the Diptera on account of the similarity in the transformations besides other considerations. There is only one family.
Family 39, Pulicidæ.—To this family belongs the numerous species of fleas which infest different kinds of animals.
The Human Flea (Pulex irritans) is familiar to every one. It gets its living by sucking our blood, and is of great annoyance, particularly in hot weather. The blisters which it raises on various parts of the body are exceedingly irritating.
The Dog Flea (Pulex canis) and the Cat Flea (Pulex felis) are distinct from the above, and are chiefly confined to those animals, although they do not disdain to vary their diet occasionally with human blood.
The Jigger or Chigoe (Sarcopsylla penetrans) is abundant in the West Indies and in South America. It is sometimes very annoying to travellers, burrowing deeply under the skin. The body of the female is capable of attaining to the dimensions of a pea.
Printed by Hazell, Watson, & Viney, Ld., London and Aylesbury.
COINS AND MEDALS
Bought, Sold, Valued or Exchanged.