160 THE CANADIAN ENTOMOLOGIST. 



THE LIFE-HISTORY OF CHRYSOPHANUS DORCAS KIRBY. 



BY WILLIAM \V. NEWCOMB, M.D., DETROIT, MICH. 



Ever since I began to study Chrysophanus dorcas in the summer of 

 1908, I have especially desired to work out its life-history, but I have only 

 accomplished this the past year (19 10). During the first season in which 

 I attempted to find the eggs* I met with considerable success, at least 

 after three or four weeks' effort, and secured an abundant supply, mostly 

 from caged females. I had not then discovered the best way of carrying 

 the eggs over the winter (this was in 1 908-1 909), with the result that in 

 the follov/ing spring they failed to hatch, except one lot, which had been 

 found in the open. Unfortunately the latter, about 25 in number, had 

 been overlooked at the time, and, when discovered, all but two or three of 

 the caterpillars, which lived only a few hours, were dead. 



It was not until the fall of 1909 that I had an opportunity to look for 

 more eggs. On October 4th I paid another visit to the Bloomfield bog, 

 and after three or four hours search on the leaves of the cut shoots of 

 Poieiitilla fruticosa I found some 150 eggs, only a few of which were 

 evidently unsound. 



The method I employed in caring for the eggs during the winter 

 ( 1 909-1910) was as follows : I placed the leaflets with the attached eggs 

 in small vials, to each of which was added two or three drops of water, 

 which was repeated the following spring whenever the leaflets began to 

 dry up. The tops of the vials were open to the air with a cover of gauze, 

 and during the winter they were kept in an outside shed, so that the con- 

 ditions njight be nearer to those to which the eggs are subject in nature. . 



The winter, fortunately, was an evenly cold one. On March 19, 

 19 10, fearing that the spring changes in temperature might affect the 

 successful hatching of the eggs, I divided them into two lots, one of which 

 was placed in an ice-box and the other lot returned to the shed. As it 

 afterwards proved, this was unnecessary, for eggs of both lots hatched well, 

 yielding healthy, vigorous caterpillars. I am now satisfied that my failure 

 in getting the eggs to hatch upon the previous attempt was due in part to 

 the changeable temperature of a warm wmter, but, undoubtedly, more 

 largely in not providing them with sufificient moisture. 



The first eggs hatched on April 10, 1910. As soon as the eggs were 

 found to be hatching, both lots were brought into the house and were, of 

 course, under the same conditions, except, perhaps, as chance left the 



*F"or information on the egg-laying- habits and other observations on the 

 biology of this species, see Can. Ent., 41 : 221-229. 

 May. 1911 



