The larval history of a second species of the Mantispides, Symphrasis varia, is partially known;[[395]] this Insect lives parasitically in the nests of a South American wasp, and each larva when full fed spins a cocoon in one of the cells of the Hymenopteron.
Sub-Fam. 5. Hemerobiides.—Wings in repose forming an angular roof over the body; the antennae moniliform or pectinate, not clavate.
The Hemerobiides consist of several minor groups about whose number and characters systematists are not very well agreed, and about some of which very little is known. We merely mention the latter, giving details as to some of the better known only.
1. The Dilarina are a small group found chiefly in the Old World, where, however, they have a wide distribution. North and South America have each one species. They are distinguished by their antennae, which, in the male, are pectinate somewhat like those of many Lepidoptera, this character being of extremely rare occurrence in the Neuroptera; the abdomen of the female terminates in a long ovipositor. The metamorphoses are not known.
2. Nymphidina: Australian Insects resembling Myrmeleonides, but having antennae without club. Metamorphoses not known.
3. Osmylina: a group of delicate and elegant Insects of small or moderate size, distinguished by the possession of three simple eyes placed on the middle of the head just above the antennae. A species of this group, Osmylus chrysops (maculatus of some authors), is an inhabitant of Britain (Fig. 212); its larva is to some extent amphibious. The metamorphoses have been observed by Dufour, Brauer, and Hagen;[[396]] it lurks under stones in or close to the water, or in moss, or on the stems of aquatic plants, and pierces and empties small Insects with its sucking-spears, which are very elongate. The young are hatched from the egg in the autumn and hibernate before becoming full grown; when this moment arrives the larva spins a round cocoon of silk mixed with sand. The pupa, or nymph, in general appearance somewhat resembles the perfect Insect, except that it is shorter and has the short wing-pads clinging close to the body. Dufour denied the existence of abdominal spiracles in either larva or imago, but, according to Hagen, they are certainly present in both. It would appear that in the larva the alimentary canal is not open beyond the chylific ventricle, and that its terminal section is modified to form a spinning apparatus.
Fig. 309.—Osmylus chrysops. A, Larva; B, side view of head of larva (after Brauer); C, pupa (after Hagen).
Osmylus and its allies, including Sisyra, are now frequently treated as a separate sub-family, Osmylides, equivalent to the Chrysopides. In it is placed a very anomalous Insect—Psectra dispar—of great rarity. The male has only two wings, the posterior pair being the merest rudiments, though the female has the four wings normally developed. Individuals of the male have been found[[397]] in widely separated localities in the Palaearctic region—Somersetshire being one of them—and also in North America.
The genus Sisyra forms for some Neuropterists the type of a separate group called Sisyrina, though by others it is placed, as we have said, with the Osmylina, though it is destitute of ocelli. The larvae of at least one species of this genus are aquatic, and have been found in abundance living in Spongilla (Ephydatia) fluviatilis, a fresh-water sponge; when discovered their nature was not at first recognised, as they possess on each ventral segment a pair of articulated appendages, looking like legs, but which are considered to be more of the nature of gills. The sucking-spears of this Insect are so long and slender as to look like hairs; whether the little animal draws its nutriment from the sponge, or merely uses this latter as a place of shelter, is not ascertained.