Sub-Order Ii Planipennia

Natural History (fig. 3).

The eggs of Neuroptera are ovoid and in several families, including the green lacewings, the female exudes a sticky secretion which she draws out into a hair-like stalk upon which the egg is laid for safety. The larvae, with few exceptions, are terrestrial or arboreal and in the Planipennia they are all characterized by the greatly drawn out mandibles and maxillae which are used for seizing and perforating the prey. The mandibles are grooved along their ventral surface and the maxil lae, which closely resemble them in form, fit one into each groove: in this way the two sets of appendages function as a pair of tubes through which the body-juices of their victims are sucked out. Larvae of the Planipennia are further remarkable for the fact that six out of their eight Malpighian tubes become transformed into silk glands, the silk being emitted through an anal spinneret. The larvae of all Neuroptera are carnivorous and mostly prey upon other forms of insect life. When fully fed those of the Planipennia construct silken cocoons and, prior to the emergence of the perfect insect, the pupa cuts open the cocoon with its mandibles and, being mobile, often travels some little distance before the imago emerges. Little is definitely known respecting the specific nature of the food of the perfect insects : many are nocturnal in habits and are attracted to lights, while most of the day-flying species are rarely seen on the wing.

Geographical Distribution.—Certain families of Neuroptera are nearly world-wide in their distribution, the Chrysopidae for example, being found in almost all extensive areas of land except ing New Zealand : the Sialidae have an almost world-wide though discontinuous range, while the Raphidiidae are apparently re stricted to the northern hemisphere. Several families, on the other hand, are almost confined to Australia which has a more complete and diverse fauna of Planipennia than any other region of the globe, although the Megaloptera are only represented there by four species. Only seven families of Neuroptera occur in the Brit ish Isles and 13 families are found in the United States.

Geological Distribution.—The Megaloptera are evidently an archaic group but their fossil remains, unless very perfect, are diffi cult to identify. The earliest undoubted remains of this sub-order have been found in the Triassic rocks of Europe. The Planipennia first appear as fossils in the Upper Permian beds of Belmont, New South \Vales, where they are represented by the genus Permi thone which appears to be an ancestor of the existing Ithonidae and possibly of other families also. The sub-order is well repre sented in the Liassic and Upper Jurassic rocks of Europe.

Economic Importance.—Neuroptera as a whole are distinctly beneficial to man in their larval stages. Larvae of the Sialidae form food for trout and other fishes, while those of the Planipen nia prey upon many soft-bodied noxious insects. In Europe and North America the most beneficial families are the Hemerobiidae, Chrysopidae and Coniopterygidae and in Australia larvae of the Ithonidae destroy numbers of Scarabaeid grubs in the soil.

the British species consult R. MacLachlan, Trans. Entomological Soc., London (i868) ; also J. J. F. X. King and J. N. Halbert in Proc. Roy. Irish. Acad., B. (Iwo). Admirable accounts of the structure and habits of Neuroptera are given by C. L. Withycombe in Trans. Entomological Soc., London (1922 and 1925). The Australian forms are of special interest and for these consult R. J. Tillyard, Proc. Linnean Soc. New South Wales (vol. xli–xliv, 1916-19). The North American species are listed by N. Banks in Trans. Amer. Entomological Soc. (1907) who has also revised the Hemerobiidae and their allies (Ibid., 5906). For accounts of the life-histories of the Chrysopidae see R. C. Smith, Mem. 58, Cornell Univ. Agric. Exp. Station and the same writer has dealt with the habits of the Hemerobiidae in Annals Entomological Soc. America (vol. xvi., 1923) ; for the North American alder flies, etc., see K. C.

Davis, Bull. 68 N.Y. State Museum. (A. D. I.)