THE PSOCID^. 351 



and carried to a part of the ant hill, where they are hatched and 

 the larvae are attended to and nursed until they are able to shift 

 for themselves. The engraving on the opposite page shows a full- 

 sized queen. The metamorphosis is very incomplete, and the larvae 

 resemble the adults except in not having full-grown wings, but 

 there are other arrests of development, and the limitation of the 

 power of reproduction is very definite. The pupae hardly differ 

 from the larvae and the adult forms. 



There are some small Neiiroptera which resemble the Terjiies 

 somewhat, but their habits are comparatively uninteresting. They 

 are the PsocidcB. They have wings which are slightly veined, large 

 heads, with three ocelli on the forehead, setiform antennae, and 

 very slender legs. These insects are found on mosses and upon 

 the trunks of trees and old walls, and a very small species inhabits 

 houses, and is particularly fond of crawling amongst old and 

 damp papers. The wings of the females never become developed, 

 and they therefore remain, as it were, in a larval condition. It 

 looks something like a little louse, and as it is said to make a 

 noise by clashing its jaws together, it has been called Psocus 

 ptilsatorins. 



The PerlidcB are very distinct as a family. They are mode- 

 rately-sized Neiiroptera, with large hind wings, which are folded 

 near their attachment. They have setiform or thread-shaped 

 antennae and well-developed jaws. Moreover, they present mani- 

 fest resemblances to the OrtJioptera, as do the Termites and the 

 Psocidce. Pictet of Geneva has paid great attention to the Euro- 

 pean species of this family. The Perlidce undergo incomplete 

 metamorphoses. The larvae are aquatic, carnivorous, active, and 

 are often provided with external respiratory organs or gills, which 

 consist of small tufts of filaments that are attached to the lower 

 part of the segments of the thorax. The nymphs or pupae, which 

 are always active, differ from the larvae in having the rudiments 

 of wings. 



When the nymphs have attained their full size they leave the 

 water and settle upon the stones or plants on the bank ; their 

 skin soon dries and splits along the back, and then the adult or 

 perfect insect scrambles out and takes to flight. The larvae 

 appear to prefer running streams, and they pass the winter at 



