THE ORTHOPTERA OF MINNESOTA. 



17 



(6) and top (c) view of the same, with the earth which ad- 

 heres to it removed. 



Each female of the Rockj- Mountain locnst lavs on an 

 average about three egg-masses; this is done at intervals of 

 two weeks, so that the egg-laying season extends from six 

 to eight weeks. 



The egg is surrounded by a shell consisting of two ku'crs, 

 of which the outer one is thin, semi-opaque, thus producing 

 the cream^'-yellow color ; highly magnifiedit appears (Fig. 5. 

 a) densely and minutely pitted or rather marked by hexa- 

 gonal concavities (Fig. 5, h). The inner and thicker laj-er 

 is deep yellow, smooth and translucent, so that the 

 form of the embryo can be plainly seen when maturing in- 

 side. The outer la^'cr is quite brittle, but the inner one very 

 tough, requiring astrong pressure to rupture it. As the em- 

 bryo within matures (Fig. 5, c), the egg-shell becomes weak- 

 ened, and the egg plump and somewdiat more transparent. 



By the muscular efforts 

 of the enclosed insect, but 

 chiefly by thorns arming 

 the hind tibiee, Fig. 5, e, 

 the shell is eventually 

 broken, and the young 

 locust pushes its way 

 through the neck of the 

 burrow towards the 

 light. 



Nearly all the eggs 

 in a pod hatch at the 

 same time, and the young 

 escape through the small 

 hole left for this purpose. 

 When the young insect 

 reaches the surface it 

 is quite weak, and still 

 surrounded by a very delicate film, which has to be first 



PK^S.— Kgj; of Rocky Mountain Locust — 

 , showing sculpture of outer s-hell; h. the 

 same very highly niagnifiecl; c. the einljryo, 

 just before hatching. (Alter Riley). 



