84 A BOOK OF INSECTS 



the fore- wings being represented by small, twisted pro- 

 cesses ; but the females are blind and grub-like. During 

 the early stages of development both sexes live within the 

 body of some other insect, usually a bee or a wasp. The 

 male ultimately becomes a free-flying insect as above 

 described, but the female remains a parasite throughout 

 life. She produces an enormous number of minute six- 

 legged larva?, and these swarm among the hairs of the 

 unfortunate host-insect, which thus becomes a source of 

 infection to her kind. 



Order XIV. — Mecoptera. 



This order includes the single family of the scorpion- 

 Hies (Pernor pidce). These insects, which are found in all 

 parts of the world, have biting mouth-parts, the mandibles 

 being inserted at the tip of a kind of beak. The antenna? 

 are long, slender, and many-jointed. The wings are long 

 and narrow, with many cross nervules ; but there are a 

 few wingless species. The males of many species have 

 the last two or three abdominal segments curiously de- 

 veloped. They are carried over the back like the tail of 

 a scorpion, whence the popular name of the group. 

 Metamorphosis is complete. The larva?, which live in 

 rotten wood, resemble caterpillars but have eight pairs of 

 prolegs. Both they and the adults are carnivorous. 



Order XV. — Trichoptera. 



The caddis-fiies were formerly included among the 

 Neuroptera ; but their structure is very distinct, and sug- 

 gests affinity with butterflies and moths. The wings and 

 body are covered with hairs. When at rest the fore-wings 

 are brought together like a roof above the hind- wings, 

 which fold up like a fan. There is a fold of membrane, 



