Part 2

_Family 18, Cynipidæ._--This family includes most of the gall flies. The number of species is very considerable. Of the great majority the females pierce with their ovipositor the tissues of plants and trees, and there deposit their eggs, from which the _larvæ_ are soon hatched. The irritation caused by this intrusion of a foreign body into the tissues produces the galls which are so commonly met with.

The galls produced by different species of flies differ greatly in form and structure. Some of them are round and smooth, like fruits, such as the cherry gall of the oak leaves, produced by the puncture of _Cynips quercus-foli_.

The most singular, however, of all the galls is perhaps the Bedeguar, which is formed on the stems of wild roses by the puncture of a small species, _Rhodites rosæ_.

_Family 19, Chalcididæ._--To this family belong many gall insects, principally found, however, in foreign countries.

The _Chalcididæ_ include a great number of small species, few exceeding half an inch in expanse. Many of these are singular in shape, and others brilliantly metallic; but, owing to their small size, they have hitherto been studied by comparatively few entomologists.

_Family 20, Proctotrypidæ._--The _Proctotrypidæ_ are probably much less numerous than the preceding family, but have been less studied, being generally smaller and more obscure in their habits; in fact, some of them share with several beetles the reputation of being the smallest insects.

_Family 21, Braconidæ._--This family is one of very great extent.

Many of the foreign species are rather large and handsome insects, often varied with black and yellow.

The best known of the _Braconidæ_ is perhaps _Microgaster glomeratus_, a small blackish species with reddish-yellow legs, which destroys the _larvæ_ of the common Cabbage Butterflies, round the dead body of which its little yellow cocoons may often be observed.

_Family 22, Ichneumonidæ._--The _Ichneumonidæ_ are rather large and slender insects, and are divided into many sub-families.

They are a very numerous group. It has been calculated that nearly 5,000 species have been described, but the data generally are very untrustworthy.

The species of _Trogus_ are rather large insects, measuring an inch or more in length. They are black with reddish legs and abdomen, and the wings are sometimes slightly dusky at the edges.

In another group, _Pimplinæ_, the ovipositor is generally very long. The best-known species is _Rhyssa persuasoria_, a blackish insect, which measures about an inch in length. This insect is met with in fir plantations, and uses its extraordinary ovipositor to drill holes in trees infested by the _larvæ_ of _Sirex gigas_, on which its own _larva_ is parasitic. The insect frequently drives its ovipositor so firmly into the wood of the tree, that it is unable to withdraw it, and perishes in this position.

_Family 23, Evaniidæ._--One of the most familiar insects belonging to this family is the _Evania appendigaster_. It is a small black insect, found in the south of Europe, and is parasitic on cockroaches. An allied British species, _Fœnus jaculator_, is a not uncommon insect found haunting the burrows of _Crabronidæ_, upon which it is probably parasitic.

_Family 24, Chrysididæ._--The Ruby-tailed Wasps, or Golden Wasps, as the _Chrysididæ_ are popularly called, are among the most brilliant of the _Hymenoptera_, most of the species being either of an intense green, blue, or fiery red.

They are small or moderate-sized insects, which are found on walls or flowers in the full heat of the sun; for, as a rule, the most brilliantly-coloured insects are diurnal in their habits.

As far as their habits are known, they deposit their eggs in the nests of other insects, chiefly _Hymenoptera_, on the _larvæ_ of which their own offspring feed.

The commonest British species is _Chrysis ignita_, which is a very variable insect, both as regards size and colouring.

TRIBE III.--PHYTOPHAGA.

The insects belonging to the third tribe of the Hymenoptera are strictly vegetable feeders. There are only two families.

_Family 25, Siricidæ._--This family includes the insects known as Tailed Wasps. It is not a very extensive family, and its species occur chiefly in Europe and North America, in both of which regions the typical genus _Sirex_ is represented by large species.

The best-known European species which is common in some parts of Britain is the great Tailed Wasp (_Sirex gigas_), a very formidable-looking insect, of which the female often measures nearly an inch and a half in length.

The general tint is black with the antennæ, the sides of the thorax and the legs and apex of the abdomen yellow. This insect lives in pine and fir woods, and the female deposits her eggs in the woody parts of the trees, into which she bores to a depth of over half an inch by means of her long ovipositor.

Another species which occurs in this country is the _Sirex juvencus_, of a steel-blue colour, but smaller than the former.

_Family 26, Tenthredinidæ._--This is a very extensive family and contains the numerous species of Saw Flies, so called because their ovipositor is in shape somewhat like a saw in appearance.

Probably the best-known species is the Gooseberry Saw Fly (_Nematus ventricosus_), whose speckled and green _larvæ_ are so injurious in gardens and orchards. This insect is yellowish in colour, and about a quarter of an inch in length.

_Tenthredo æthiops_, a small black species, deposits its eggs upon fruit trees.

Many other species live on different kinds of plants and trees.

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._

Family 1. Myrmeleontidæ or Ant Lions. Family 2. Hemerobiidæ or Lacewing Flies. Family 3. Mantispidæ or Mantis Flies. Family 4. Sialidæ or Sialis Flies. Family 5. Raphiidæ or Snake Flies. Family 6. Panorpidæ or Scorpion Flies.

_Sub-Order 2.--Trichoptera_ (or Caddis Flies).

Family 1. Inæquipalpia or Large Caddis Flies.

Sub-family 1. Phryganeidæ. Sub-family 2. Limnophilidæ. Sub-family 3. Sericostomidæ.

Family 2. Æquipalpia or Little Caddis Flies.

Sub-family 1. Leptoceridæ. Sub-family 2. Hydropsychidæ. Sub-family 3. Rhyacophilidæ. Sub-family 4. Hydroptilidæ.

_Sub-Order 3.--Pseudo-Neuroptera._

TRIBE I.--ORNOPTERA (or Dragon Flies).

Family 1. Libellulinæ or Great Dragon Flies.

Sub-family 1. Libellulidæ or Libellulines. Sub-family 2. Cordulidæ or Cordulines. Sub-family 3. Æschnidæ or Æschnines. Sub-family 4. Gomphidæ or Gomphines.

Family 2. Agroninæ or Slender Dragon Flies.

Sub-family 1. Agronidæ or Agronines. Sub-family 2. Calopterygidæ or Calopterygines.

TRIBE II.--SUBULICORNIA.

Family 3. Ephemeridæ or Day Flies.

TRIBE III.--PLECOPTERA.

Family 4. Perlidæ or Stone Flies.

TRIBE IV.--CORRODENTIA.

Family 5. Psocidæ or Book Mites. Family 6. Embiidæ or Agile Mites.

TRIBE V.--SOCIALIA.

Family 7. Termitiæ or White Ants.

TRIBE VI.--PHYSOPODA (or Thrips).

Family 8. Tubulifera. Family 9. Terebrantia.

TRIBE VII.--MALLOPHAGA (or Bird-lice).

Family 10. Philopteridæ. Family 11. Liotheidæ.

TRIBE VIII.--THYSANURA (or Bristle-tails).

Family 12. Lepismidæ. Family 13. Campodeidæ. Family 14. Japygidæ.

TRIBE IX.--COLLEMBOLA (or Spring-tails).

Family 15. Smynthuridæ. Family 16. Papyriidæ. Family 17. Degeeriadæ. Family 18. Poduridæ. Family 19. Amouridæ.

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.