THE CANADIAN ENTOMOLOGIST. 161 



leaves in one vial slightly damper than those in another. The eggs con- 

 tinued to hatch until April 25th, when a total of 109 caterpillars had 

 emerged. The majority came out on the i8th, 19th and 20th: 19, 31 and 

 15 caterpillars, respectively. 



I think one observation indicates quite clearly the necessity of 

 providing sufficient moisture for the eggs. Up to April 15th 24 eggs had 

 given caterpillars from the lot that had been kept in the shed all the time. 

 No more hatched from this lot until the 23rd, although in this interval a 

 majority of all the caterpillars had come out of the eggs that had been 

 kept for a period in an ice-box. On the morning of April 23rd I moistened 

 the leaves in the vial, which had become dry and from which no eggs had 

 hatched for the past eight days. At 10 p.m. on the same day three more 

 caterpillars had hatched, thus showing quite conclusively, I think, the 

 need of moisture, at least, during the period of hatching. This is what we 

 should expect, as the fallen leaves lying beneath the cinquefoil bushes 

 must become very wet in the spring from the melting snow and ice. 



At first I did not know the best way of caring for the caterpillars, for 

 they were so small. After a few days, however, I hit upon a plan which 

 proved very successful. 



P'or breeding cages I used a large number of tube or shell vials of 

 two sizes, 25 X 60 mm. and 35 X72 mm. In each of these was placed a 

 layer of sand to the depth of about 15 mm., which was kept well moistened. 

 To prevent the escape of the caterpillars, the top of each vial was covered 

 with a thin piece of gauze, held in place by a rubber band. A tiny spray 

 of cinquefoil stripped of its lower leaves, pushed into the wet sand, 

 furnished food. To transfer the caterpillars I used a wooden match 

 sharpened at one end. 



For those caterpillars which I desired to keep under special observa- 

 tion, I used the smaller vials, a single specimen to a vial. In providing 

 individual homes for them in this way I could readily keep track of each 

 caterpillar, notwithstanding its small size, and, best of all, as the food-plant 

 kept fresh and green, it was only necessary to disturb the caterpillars about 

 once in four or five days until after the third ecdysis. Then, as they were 

 eating more, food had to be supplied oftener. In the larger vials I kept 

 several caterpillars, but I could not, of course, watch each individual one 

 so closely. Fortunately, I had a good supply of Potentilla fruticosa in 

 my garden, for the caterpillars preferred the tender opening leaflets to the 

 fully-opened leaves. 



