| Fig. 5.—An Ichneumon Parasite, Pimpla annulipes, showing male and female abdomen. | Fig. 6.—A Chalcid Parasite, Chalcis flavipes. |
The insects of this section must be considered essentially beneficial to man, notwithstanding the occasional sting of a bee or wasp, the boring of a carpenter bee, or the importunities of the omnipresent ant. Not only do they furnish us with honey and wax, but they play so important a part in the destruction of insects injurious to vegetation that they may be looked upon as God-appointed guards over the vegetal kingdom—carrying the pollen from plant to plant, and insuring the fertilization of diœcious species, and the cross-fertilization of others; and being ever ready to clear them of herbivorous worms which gnaw and destroy. The whole section is well characterized by the uniformly maggot-like nature of the larva. The transformations are complete, but the chitinous larval covering is often so very thin and delicate that the budding of the members, or gradual growth of the pupa underneath, is quite plainly visible, and the skin often peels off in delicate flakes, so that the transition from larva to pupa is not so marked and sudden as in those insects which have thicker skins.
Fig. 7.—A Horn-tail, Tremex columba. a, larva, showing Thalessa larva attached to its side; b, head of larva, front view, enlarged; c, female pupa, ventral view; d, male pupa, ventral view; e, adult female—all slightly enlarged.
Fig. 8.—Saw-fly and Larva. Pristiphora grossulariæ;
a, larva; b, imago, Walsh.
“The terebrantine Hymenoptera, or Piercers, are again divisible into two subsections: first, the Entomophaga, which are, likewise, with the exception of a few gall-makers, beneficial to man, and include the parasitic families, and the gall-flies; second, the Phytophaga, comprising the Horn-tails (Uroceridæ), and the Saw-flies (Tenthredinidæ), all of which are vegetable feeders in the larval state, those of the first family boring into trees, and those of the second either feeding externally on leaves or inclosed in galls. They are at once distinguished from the other Hymenoptera by the larvæ having true legs, which, however, in the case of the Horn-tails, are very small and exarticulate. The larvæ of many Saw-flies have, besides, prolegs, which are, however, always distinguishable from those of Lepidopterous larvæ by being more numerous and by having no hooks.
Fig. 9.—A Chafer,
Cotalpa lanigera. (After Packard.)