18 



BULLETIN 967, U. S. DEPARTMENT OF AGEICULTUKE. 



been reared came from coarctate larvse that were collected during the 

 fall and winter. 



Seven mature coarctate larvse of one type, collected during the 

 winter of 1913-14 were placed on soil in a perforated tin box. Dur- 

 ing the summer the box was buried in the insectary at a depth of 

 about 2 inches and forgotten. The writer chanced upon it again 

 November 25, 1914, finding in it six coarctate larvae, one dead third 

 larva, and seven cast coarctate skins. Only one explanation is pos- 

 sible. The coarctate larvse all transformed to the third larvae, and 

 six of them reverted to the coarctate condition again. The seventh 

 perished. On May 30, 1915, the six coarctate 

 larvse were separated into two lots of three each. 

 One lot was placed in dry earth, the other in 

 clamp earth. The former showed no signs of 

 activity. Of those in moist earth, one had de- 

 cayed by July 2, another had transformed to 

 third larva, and the third specimen remained 

 unchanged and apparently healthy. The third 

 larva continued its transformations, and on July 

 24 yielded an adult of Epicauta sericans. The 

 four unchanged coarctate larvse were stored in 

 dry soil until the spring of 1916. Upon being 

 moistened they decayed at once. 



A coarctate larva obtained during the winter 



of 1913-14 did not yield the adult until July 7, 



1915. This proved to be Macrobasis immaculata. 



Eiley'^ reports cases of retarded development in Epicauta vittata 



(figs. 20, 21). From the same batch of eggs he had beetles mature 



in one, two, and three years. Regarding one which required three 



years he wrote as follows: 



In this case the individual, tliougli submitted to exactly the same conditions 

 as the other specimens, which had simultaneously hatched with it — ^but which 

 went through all their transformations within either one or two years — re- 

 mained dormant for nearly three years, with their repeated changes of season 

 and temperature. With the exception of the first winter, when it was kept 

 indoors without freezing and when development should have been presumably 

 hastened, the specimen was kept in a tin box buried the proper distance beneath 

 the gi'ound out of doors, so as to be as nearly as possible under natural con- 

 ditions. 



Continuing the discussion of retarded development, he says: 



In the case of our blister-beetles, depending as they do on locust eggs, and 

 especially in the case of those which feed particularly on the eggs of migratory 

 species, it is not difficult to perceive how this trait may prove serviceable to 

 the species possessing it. Migratory locusts occur in immense numbers in some 



« Riley, C. V., Packard, A. S., and Thomas, Cyrus. Second Report, U. S. Ent. Comm. 

 Cept. Interior, 1878 and 1879, pp. 260-261. 1880. 



Pig. 20.- 

 beetle 

 tata) : 

 beetle 

 larged 



—Striped blister 



(Epicauta vit- 



u. Female 



I), eggs. En- 



( Chittenden.) 



