In a few families of beetles, both the adults and larvae are fitted for aquatic life. Well known among these are the shining whirligig beetles.
Hymenoptera
Bees, Wasps, Ants, Sawflies
Insects typically with two pairs of wings; antennae of various lengths; chewing mouthparts; without tails. A typical member of this group is the wasp Vespula maculata (Linnaeus), [fig. 56]. Many adult members of the group are atypical in that they lack wings; these include all the true ants, [fig. 57], which are without wings except for the sexual forms produced at the time of the nuptial flights. Forms of one species, Lasius interjectus Mayr, are shown in [fig. 58]. The wings, when developed, are without scales; the venation is much less extensive than in the Neuroptera; and the hind wings differ in shape and size from the front wings. The young stages of the Hymenoptera are caterpillar-like or grublike, entirely different from the adults.
This very large order includes such well-known forms as the bees, as well as the wasps and the ants, mentioned above. In addition, it includes the sawflies, whose caterpillar-like larvae are extensive defoliators of a large number of native and cultivated plants and shrubs; the large and varied groups of parasitic wasps that exert great influence in the natural control of a tremendous number of other insects; and a large number of gall-making wasps, whose galls are especially conspicuous on oak trees. A parasitic wasp of the genus Opius is shown in [fig. 59]. The parasitic wasps are extremely diverse in size, shape, and habits. They range in size between 0.02 and 2.0 inches.
Fig. 56.—Hymenoptera. Vespula maculata, the common bald-faced hornet. Actual length 0.8 inch.
Fig. 57.—Hymenoptera. A worker ant belonging to the genus Formica. This form lacks wings. Actual length 0.3 inch.
Mecoptera
Scorpionflies
Insects typically with two similar pairs of delicate wings, each wing with a network of veins. In repose the wings are laid either tentlike over the back or almost flat. The mouthparts are fitted for chewing and usually are lengthened into a beaklike structure, as in Panorpa chelata Carpenter, [fig. 60]. The larvae, seldom found, live in damp woods. The adults of most winged species occurring in Illinois are about 0.5 inch long. They are active in early summer in shady woods, flying through the undergrowth. Adults of the genus Boreus are smaller and they have very short, veinless wings. They emerge in the winter and early spring; these little metallic black insects often hop around on late winter snow. In certain genera, the adult male genitalia form a bulb-like structure at the end of the body, as in [fig. 60]. This structure is harmless but, because it resembles a scorpion’s sting, insects of these genera are given the name scorpionflies.