122 



ZOOLOGY. 



The Dragon Flies (Libellulidoe) fly about inces- 

 santly from place to place on bright warm days, and 

 catch a large number of insects, especially butterflies 

 and flies, among which are many that are harmful. 

 The larvae live in water, and feed on insects and such 

 small deer, which, however, are of no importance to 

 forestry or agriculture. They also devour fish-spawn, 

 and may therefore be injurious in that way. 



The lace Flies (Hemerohidce) when at rest are 

 covered as with a roof by their fore and hind wings, 

 which are almost alike, clear as glass, and finely 

 veined. Head tolerably large, eyes large, abdomen 

 elongated and slender. The extremely rapacious 

 larvse (Fig. 86, b) feed on the juices of the bodies of 

 other insects, which they suck up by means of a 



(If 1} 



Fig. 86.— The Common Lace Fly (Chrysnpa vulgaris) : a, eggs ; b, the larva ; 

 c, cocoon; (2. pupa contained in the same; e, open cocoon ;,/*, adult Insect; 

 a, c, e, natural size ; d, enlarged and natural size ; b and/ enlarged. 



pincer-like organ situated on either side of the mouth. 

 The two pincers are perforated, and the tubes open 

 on each side into the gullet ; the body juices of the 

 insects attacked thus flow into the gut of the larva. 

 This is strongly built, and always much thicker and 

 larger than the adult insect. Metamorphosis com- 

 plete. Three genera belong to the lace flies : — 



1. The delicate greenish, or greenish yellow, ill- 

 smelling Gold-eyed Lace Flies (Ghrysopa), the larvse of 

 which chiefly feed on plant lice (a few species on 

 caterpillars, also, and other small insect larvae). 



2. The Aphis Lions {Hevierobius : H. hirtus, with 



