448 
succeeding the head. In the latter, including the Orthop- 
tera, Hemiptera, Homoptera, and certain Neuroptera, 
the body, legs, and antennz are nearly similar in their 
form to those of the perfect insect, but the wings are 
wanting.” S 
Hleteromorpha Homomorpha 
Hymenoptera Euplexoptera 
Strepsiptera Orthoptera 
Coleoptera Hemiptera 
Trichoptera Homoptera 
Diptera Thysanoptera 
Aphaniptera 
Lepidoptera 
Neuroptera 
‘But though the Homomorphic insectsdo not passthrough 
such striking changes of form as those belonging to the 
other series, and are active throughout life, still it was until 
within the last few years generally (though erroneously) 
considered that in them, as in the Heteromorpha, the life 
fellinto four distinct periods ; those of (1) the egg, (2) the 
larva characterised by the absence of wings, (3) the pupa 
with imperfect wings, and (4) the imago or perfect insect. 
I have, however, elsewhere * shown that there are 
not, as a matter of fact, four well-marked stages, and four 
only, but that in many cases the process is much more 
gradual. 
The Hymenoptera are among the most interesting of 
insects. To this order belong the gallflies, the sawflies, 
the ichneumons, and above all, the ants and bees. We 
are accustomed to class the Anthropoid apes next to man 
in the scale of creation, but if we areto judge animals by 
their works, the chimpanzee and the gorilla must cer- 
tainly give place to the bee and to the ant. The larve of 
the sawflies, which live on leaves, and of the Sirecidze or 
long-tailed wasps, which feed on wood, are very much like 
caterpillars, having three pairs of legs, and in the former 
‘ case abdominal prolegs as well; but in the great majo- 
rity of Hymenoptera the larve are legless, fleshy grubs 
(Plate 2, Figs. 7-9) ; and the various modes by which the 
females provide for or secure them a sufficient supply of 
appropriate nourishment, constitutes one of the most 
interesting pages of Natural History. 
The pupz are inactive, and show distinctly all the 
limbs of the perfect insect, encased in distinct sheaths, 
and folded on the breast. 
In the perfect state these insects are highly organised 
and very active. The working ants and some few species 
are wingless, but the great majority have four strong mem- 
branous wings, a character distinguishing them at once 
from the true flies, which have only one pair of wings. 
The species of Hymenoptera are very numerous ; in this 
country alone there are about 3,000 kinds, most of which 
are very small. 
The sawflies are so called because they possess at the 
end of the body a curious organ, corresponding to the 
sting of a wasp, but which is in the form of a fine- 
toothed saw. With this instrument the female -sawfly 
cuts a slit in the stem or leaf of a plant, into which she 
introduces her egg. 
The larva much resembles a caterpillar, both in form 
and habits. To this group belongs the nigger, or black 
caterpillar of the turnip, which is often in sufficient num- 
bers to do much mischief. Some species of this group 
make galls, but the greater number of galls are formed 
by insects of another family, the Cynipidz (Plate 1, 
Fig. 7). In this family the female is provided with an 
organ corresponding to the saw of the sawfly, but resem- 
bling a needle. With this she. stings or punctures the 
surface of leaves, buds, stalks, or even roots of various 
plants. In the wound thus produced she lays one or 
more eggs. The effects of this proceeding, and particu- 
larly of the irritating fluid which she injects into the 
* Linnwan Transactions, 1863—‘‘ On the Developmentjof Chlocon,” 
NATURE 
[April 10, 1873 
wound, is to produce a tumour or gall, within which the 
egg hatches, and on which the larva, a thick fleshy grub, 
(Plate 2, Fig. 7) feeds. In some species each gall con- 
tains asingle larva; in others, several livetogether. The 
oak supports several kinds of gallflies ; one forms the well- 
known oakapple, one forms a small swelling on the leaf 
resembling a currant, another produces a gall somewhat 
resembling an acorn, another attacks the root ; the species 
making those bullet-like galls, which are now so common, 
has only existed for a few years in this country; the 
beautiful little spangles so common in autumn on the 
under side of oak-leaves are the work of another species, 
the Cynips longipennis, When the larva is full grown, it 
eats through the gall, falls to the earth, and turns into a 
chrysalis. Onecurious point about this group is, that in 
some of the commonest species the females alone are 
known, no one yet having ever succeeded in finding a 
male, 
Another great group of the Hymenoptera is that of the 
ichneumons ; the females lay their eggs either in or on 
other insects, within the bodies of which the larvee live. 
They are thick, fleshy, legless grubs, and feed on the 
fatty tissues of their hosts, but do not attack the vital 
organs. When full grown, they eat their way through the 
skin of the insect, and turn into chrysalides. Almost 
every kind of insect is subject to the attacks of these 
horrid little creatures, which, however, are no doubt use- 
ful in preventing the too great multiplication of insects, 
and especially of caterpillars. Some species are so 
minute that they even lay their eggs within those of other 
insects. The larvz of these genera assume very curious 
forms. 
But of all Hymenoptera, the group containing the 
ant, the bee, and the wasp is the most interesting. This 
is especially the case with the social species, though the 
solitary ones also are extremely remarkable, The solitary 
bee or wasp, for instance, forms a cell generally in the 
ground, places in it a sufficient amount of food, lays an 
egg, and closes it up. In the case of bees, the food 
consists of honey ; in that of wasps, the larva requires ~ 
animal food, and the mother therefore places a certain 
number of insects in the cell, each species having its own 
special prey, some selecting small caterpillars, some beetles, 
some spiders. Cerceris bupresticida,as its name denotes, 
attacks beetles belonging to the genus Buprestis. Now 
if the Cerceris were to kill the beetle before placing it in 
the cell, it would decay, and the young larva when hatched 
would find only a mass of corruption. On the other 
hand, if the beetle were buried uninjured, in its 
struggles to escape it would be almost certain to de- 
stroy the egg. The wasp has, however, the curious 
instinct of stinging its prey just in the centre of the ner- 
vous system, thus depriving it of motion, and let us hope 
of suffering, but not killing it; when, therefore, the 
young larva leaves the egg, it finds ready a sufficient store 
of wholesome food. Other wasps, like the bees and ants, 
are social, and dwell together in communities. They live 
for one season, dying in autumn, except some of the 
females, which hybernate, awaking in the spring and 
forming new colonies, Even these, however, under ordi- 
nary circumstances, never live through a second winter. 
One specimen which I kept tame through last spring and 
summer, lived until the end of February, but then died. 
The larve of wasps are fat, fleshy, legless grubs. When they 
are full grown they spin for themselves a silken covering, 
within which they turn into chrysales. The oval bodies 
which are so numerous in ants’ nests, and which are 
generally called ants’ eggs, are really cocoons, not 
eggs. Ants are very fond of the honey-dew which is 
formed by the Aphides, and have been seen to tap the 
Aphides with their antenna, as if to induce them to 
emit some of the sweet secretion. There is a species of 
Aphis, which lives on the roots of grass, and some ants 
collect these into their nests, keeping them, in fact, just 
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