The Hymenoptera belongs to one of the most interesting and extensive orders of insects. The structure and habits of the different species which it includes are very various. Their marvellous instincts have excited the admiration and wonderment of the philosophers of all ages. They are, indeed, by far the most intelligent of insects, being greatly in advance of any other group known to exist. The Hymenoptera are mandibulate insects, their mouths being formed for biting, and they undergo complete metamorphoses. Perhaps the most striking external distinctive character is to be found in the structure of the wings, both pairs of which are membranous; and another peculiarity of equal importance is the condition of the prothorax, which is reduced to very small dimensions. In the majority of the Hymenoptera the females are provided with stings, which serve many purposes, independently of weapons of defence. Many families, however, do not possess stings.
Many of the Hymenoptera feed on plants and trees, but probably the greater number are parasitic on other insects.
Fig. 6.—Pimpla Turionellæ (Mag.)
This order includes the bees, wasps, ants, saw flies, gall flies, ichneumon flies, and many other familiar insects.
The following will show the principal characteristics of each group into which the order has been divided.
[Tribe 1, Aculeata.]—Generally social insects, consisting of males, females, and neuters. Ovipositor modified into a sting. Larvæ, footless grubs.
[Tribe 2, Entomophaga.]—Mostly parasitic on the eggs and larvæ of other insects. Ovipositor used as a borer. Larvæ, footless grubs.
[Tribe 3, Phytophaga.]—Principally vegetable feeders. Ovipositor used as a borer. Larvæ having six or more legs.
TABULAR VIEW
OF THE
PRINCIPAL FAMILIES OF THE HYMENOPTERA.