NEUROPTERA. 157 



are terrestrial, feed on plant lice. Very useful and entertaining in their habits are the 

 laoe-winged flies, whose larvas are caUed " aphis-lions," and " ant-lions." The common- 

 est example is the delicate green, golden-eyed, lace-winged fly, so common everywhere, 

 and so offensive in its odor when handled. These delicate, graceful, gauzy-winged 

 gems have as their sole protection an abominable odor, which they leave upon the fin- 

 gers when rudely handled, and it is doubtless their bad taste which prevents their being 

 snapped up by birds ; for one may notice how extremely exposed to the attacks of 

 birds are these insects. The lace-winged flies, when young, do the greatest service to 

 gardeners, from their exemplary habit of devouring plant-lice, or Aphides. The larvae 

 of different species of Hemerobius, which are common among evergreen and other 

 trees, after piercing with their long, sickle-like jaws the bodies of the Aphides, make 

 a thick, loose mantle of the dried skins of their victims. 



It is well known that the Aphides congregate in great numbers on the stems or 

 leaves of plants ; among them the common golden-eyed, lace-winged fly ( Chrysopa 

 OGulata) lays its eggs. We have observed that the female Chrysopa lays between 

 forty and fifty eggs, which are placed upon long, 

 slender stalks, so as to be out of the reach of wander- 

 ing, predaceous mites, and other egg-eating insects. 

 One Chrysopa, which was observed in confinement, 



,.,./. ^1 , , ^. Fig. 228 — Chrysopa aui eggs. 



laid lorty-six eggs; another, whose reproductive 



powers were evidently impaired, laid eighteen stalks, upon only nine of which were 

 well-developed eggs, the remaining nine being barren stalks, some only half the usual 

 height, while others were provided with the knob, formed of cement, at the end, on 

 which the egg is ordinarily fastened. It is evident that the fly, in depositing an egg, 

 first attaches the stalk to the surface of the leaf, and afterwards forces the egg from 

 her oviduct and attaches it by the mass of cement to the end of the stalk, as in one 

 case an egg was glued to the end of the stalk very much out of centre, the insect's 

 ovipositor not having aimed straight, so to speak, at the mass of cement. The eggs 

 are at first of a pale, delicate green, turning grayish just before the embryo hatches. 



The eggs are laid throughout the summer, so that there is a constant supply of 

 aphis-lions, and the time of embryonic growth is limited, as the young appear in six 

 or seven days from the time the eggs are laid. When the larva is ready to turn to a 

 chrysalis it spins a round cocoon of silk, and two weeks later the winged fly appears. 



The species of Semerohius have essentially the same habits as those of Chrysopa, 

 but they are smaller, obscurely colored, and less frequently met with, occurring in 

 forests. 



Another notable form is Mantispa, so-called from its mimicry of the praying 

 insect, or Mantis. The neck or prothorax is remarkably long, but most remarkable are 

 its fore-legs, which are very large, and bent, like those of Mantis, in the attitude of 

 prayer ; but in reality they are admirably adapted for seizing, and retaining in their 

 grasp, other insects. 



The metamorphosis of Mantispa is of unusual interest, inasmuch as the larva passes 

 through two stages, with quite different habits in each, before spinning its cocoon and 

 assuming the pupa state. Thus far we are acquainted only with the life-history of an 

 European species, Mantispa styriaca, which has been worked out by Brauer, an 

 Austrian entomologist of distinction. The rose-red eggs are laid in great numbers, in 

 July, and, like those of Chrysopa, are laid on long, slender stalks. The larva hatclies 

 in twenty-one days, and spends the winter without taking food. In the succeeding 



