INSECTS 379 



devoid, however, of pro-legs, while at the end of its tail is a pair 

 of pincers by which it can attach itself firmly to the case. The 

 food is mainly of vegetable nature. After from seven to 

 ten months the larva closes the opening of the tube with silk 

 and passes into the pupa stage, which, after remaining quiescent 

 for two or three weeks, bites its way out of the case and swims 

 on its back to some plant or other object up which it can climb 

 out of the water. The pupal skin then splits, and the caddis-fly 

 emerges. 



4. White Ants, more correctly called Termites, since they 

 have nothing whatever to do with ants proper, are but too well 

 known to the inhabitants of tropical countries on account of the 

 havoc they work with wooden furniture and the like. They are 

 social insects, living in communities organized in an extraordinarily 

 complex manner, about which particulars will be given in the 

 sequel. In every community both winged and wingless individuals 

 may be found, the former possessing four very long narrow wings 

 of the kind characteristic of the order, which are held flat on the 

 back when at rest. There is but a slight metamorphosis. Two 

 species are found in South Europe {Calotermes flavicollis and 

 Termes lucifugus), but the most remarkable forms are natives 

 of tropical Africa, and some of these (e.g. Termes bellicosus) 

 construct nests of earth which may be as much as 14 feet 

 high. 



Book-Lice are minute forms of somewhat doubtful affinities, 

 and most familiarly known by the wingless species giving the 

 name to the group, but also including the " death watches " 

 {Atropos divinatoria and others), commonly reputed by the super- 

 stitious to herald death by a ticking noise, though the sound is 

 more probably produced by a wood-eating beetle (Anobium). 

 The winged species, which are the most numerous, are to be 

 found feeding on lichens, fungi, and other plants. Of the four 

 membranous wings, which are provided with but few nervures, 

 the hind ones are much the smaller. The antennae are very long. 

 There is but a slight metamorphosis. Among the British winged 

 species may be mentioned Psocus fasciatus. 



5, Biting- Lice are small wingless, large -headed creatures 

 which live on the skins of birds and mammals, and must care- 

 fully be distinguished from ordinary lice (p. 354), in which the 

 mouth-parts are adapted for piercing and sucking. The common 



