Natural History and Transformations. 73 



which are to be laid at future periods. This, I repeat, can 

 be determined by any one who will take the trouble to 

 carefully examine a few females when laying. But just 

 how often, or how many eggs each one lays, is more diffi- 

 cult to determine. With spretus I have been able to 

 make comparatively few experiments, but on three differ- 

 ent occasions I obtained two pods from single females, 

 laid at intervals of 18, 21 and 26 days respectively. I 

 have, however, made extended experiments with its close 

 congeners, femur -rubrum and Atlanis, and in two cases, 

 with the former, have obtained four different pods from one 

 female, the laying covering periods of 58 and 62 days, and 

 the total number of eggs laid being 96 in the one case 

 and 110 in the other. A number of both species laid 

 three times, but most of them — owing, perhaps, to their 

 being confined — laid but twice. They couple with the 

 male in the intervals of oviposition, and I have no doubt 

 but that, as in most other species of animals, there is great 

 difference in the degree of individual prolificacy. We may, 

 therefore, feel tolerably confident that the Rocky Mountain 

 Locust will sometimes form as many as four egg-pods. 



The time required for drilling the hole and completing 

 the pod will vary according to the season and the temper- 

 ature. During the latter part of October, or early in No- 

 vember last year, when there was frost at night and the 

 insects did not rouse from their chilled inactivity until 9 

 o'clock a. m., the females scarcely had time to complete the 

 process during the four or five warmer hours of the day ; 

 but with a higher temperature not more than from two 

 to three hours would be required. 



HOW THE YOUNG LOCUST ESCAPES FROM THE EGG. 



Carefully examined, the egg-shell is found to consist of 

 two layers. The outer layer which is thin, semi-opaque, 



