THE MECAPTEBA, 
123 
cocoon. Such are the lace-winged fly (Pig. 154), the ant- 
lion, and Corydalus. The aphis-lion is the larva of the 
lace-winged fly, and devours large numbers of plant-lice. 
Order 10. Mecoptera. — The type of this group is Panorpa, 
Order 11. Trichoptera. — The case-worms are the larvae of 
moth-like insects called Caddis-flies. Their wings are veined 
much as in the smaller moths. Their larvae resemble cater- 
pillars, but live in water, in cases (Fig. 155). 
Order 12. Coleoptera. — In beetles the fore-wings are thick- 
ened, not used in flight, and form sheaths {elytra)^ which 
Fia. 156.— Metamorphosis of the May-beetle; 2, larva; 1, pupa. 
protect the under or hinder pair. Their young are called 
grubs; the pupae usually rest in cocoons of earth, etc., their 
metamorphosis being complete (Fig. 156). The tiger and 
ground beetles have long sharp jaws for seizing other 
insects; they are the tigers of the insect world. The bury- 
ing-beetles are scavengers, and useful insects they are. 
The leaf-beetles are very numerous, and comprise as in the 
potato-beetles (Fig. 157) some of our most destructive in- 
sects. Injurious to trees and fruit are the boring-beetles 
and the weevils. The latter with their long beak, at the 
