HARMFUL INSECTS 133 
enters on the pupa stage, and at the end of about a 
fortnight emerges as a beetle. 
The Crane-fly, commonly called Daddy-longlegs, pro- 
duces larvae known as leather-jackets. The eggs are 
deposited just be- 
neath the surface of 
the soil, and the 
larvae pass the win- 
ter under - ground. 
They are extremely 
destructive to many 
crops and to grass, 
devouring and des-. 
troying the roots of 
the plants. 
The Hessian 
Fly has long been 
a deadly enemy of 
the grower of Wheat, 
and Barley. 
Fig. 90.—Crane Fly. (1) Eggs, (2) Grub, The eggs, which 
(3) Chrysalis, (4) Perfect Fly. are minute and re d, 
are laid upon the leaves of these plants. The larva which 
issues from the egg feeds upon the leaf-sap, and, when 
full-fed, .enters on the pupa stage within the plant itself. 
There it remains for a longer or shorter time and finally . 
emerges a fly. 
The Bot-fly of the horse in both the fully developed 
and larval stages is extremely troublesome to this animal. 
The female hovering about the horse touches his skin 
with the tip of her abdomen. At that instant a sticky 
egg is passed out and firmly glued to one of the hairs near 
the tip. The sticky substance with which the egg is 
covered, on being exposed to the air, sets hard and cements 
