228 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



ber of eggs produced by a well-developed locust will range from 100 to 

 loO, if we consider species generally. We have counted 171 in one mass 

 of Caloptenus differ e ntialis ; from 120 to 130 in those of (Edipoda phance- 

 coptera, and about 120 in that of Acridium Americanum. The great 

 probability is that the eggs of such species are all laid at once. In spe- 

 cies like spretus, which rarely lay more than 30 eggs in one mass, it were 

 natural to infer that different layings take place, even did the facts at 

 hand not prove such to be the case. In 1876 the insects were pushing 

 continuously southward from the middle of August till the end of Oc- 

 tober, and during most of this time they were laying eggs. In fact, 

 throughout the country invaded, from Minnesota to South Texas, they 

 continued laying till frost, and we know from examinations that many 

 of them perished before all the ova had been disposed of. Stragglers 

 were even noticed in Texas as late as December. 



To sum up the inquiry, we would give it as our belief that the laying 

 season normally extends from six to eight weeks j that it may be short- 

 ened or lengthened by conditions of weather and climate; that fecun- 

 dity is materially affected by the same conditions ; that the average 

 number of egg-masses formed is three ; and that the average interval 

 between the periods of laying by the same female is two weeks. 



THE HATCHINa PROCESS. 



All that pertains to embryology proper will be found in Chapter 

 IX, and we shall make here but a brief reference to the character of the 



egg in order to more clearly illus- 

 trate the process of hatching. "Care- 

 f u lly examined , the egg-shell is foun d 

 to consist of two layers. The outer 

 layer, which is thin, semi-opaque, 

 and gives the pale, cream-yellow 

 color, is seen by aid of a high mag- 

 nifying power to be densely, minute- 

 ly, and shallowly pitted ; or, to use 

 still more exact language, the whole 

 surface is netted with minute and 

 more or less irregular, hexagonal 

 ridges (Fig. 5, a, h). It is a mere 

 covering of excreted matter, sim- 

 ilar in nature to the mucous or 

 sebific fluid already described, which 

 binds the eggs together. The inner 

 layer (or chorion) is thicker, of a 

 deeper yellow, and perfectly smooth. 

 It is also translucent, so that, as 

 the hatching period approaches, the 

 form and members of the embryon may be distinctly discerned through 



Fig. 5.— Egg of Eocky Mountain Locust.— a, 

 showing sculpture of outer shell; b, the same, 

 very highly magnified; c. the inner ehell, just be- 

 fore hatching — ( Alier Pdley.) 



