THE HYMENOPTERA. I 65 
or less well developed. The mandibles are always strong, but 
differ much in form, according to the habits of the species. The 
jaws and the lower lip, which are usually rather short, elongate 
in some kinds which pump up honey, and they then form a kind 
of trunk, which is doubled up against the thorax when it is not 
wanted. The thorax is swollen out, as it were, and its integu- 
ment is solid and dense, like a cuirass; and the muscles which 
produce the movements of the wings, and which are attached to 
it within, are very large and strong. The legs have moderate 
powers; and, although these insects are better able to walk than 
the Lepidoptera, still they cannot be called, in comparison with 
others, either walking or jumping insects. Their best means of 
locomotion are their wings; and the insects fully understand this, 
for even when they have to walk a short distance the wings assist 
the legs, and help the not very heavy body to move along. The 
only Hymenoptera that can be called true walkers are those that 
have no wings, like the neuter ants, and their agility 1s very won- 
derful. The legs are often provided with accessory structures, 
and are, moreover, modified so as to enable certain species to 
live particular lives. 
Most of these insects have a very movable abdomen attached 
to the thorax by a very narrow waist, which is notoriously small, 
in the wasp tribe for instance, The females have a long and 
slender tube at the end of the abdomen, which is of great im- 
portance to them, either as an ovipositor or as a sting. The 
weapon of offence is invariably formed by the same kind of 
structures in all insects that possess it, and Lacaze Duthiers 
has discovered it in a rudimentary condition even amongst the 
Lepidoptera. These structures are modified in various manners, 
but the same end is always kept in view, and the resulting organ 
is of the greatest importance. 
The Hymenoptera undergo complete metamorphoses. Some 
larve are usually soft and white, and, as they have no legs, they 
look like worms; but some exceptional kinds have small fore and 
hind legs like caterpillars. Almost all the larve, when they have 
attained their full growth, shut themselves up in a cocoon, which 
they make up with the silken stuff they are able to produce, and 
then are transformed into pupe. 
