51 



adult butterflies developing from the first brood of larvae begin to breed 

 at the end of June and fly until late in August. In hop-growing 

 regions the majority of the eggs of this set of butterflies are laid upon 

 hop vines. The resulting caterpillars feed until well on in August, and 

 the butterflies which are to hibernate make their appearance from the 

 latter part of this month until the latter part of September. They 

 enter hibernating quarters almost immediately, since they are rarely 

 seen in October. 



The eggs, as seen from the plate, are very similar in shape and size 

 to those of the semicolon butterfly, and are laid in somewhat similar 

 depending columns, which vary in number from 2 to 9 eggs. Frequently 

 several of these columns will be found upon a single leaf, usually upon 

 the under surface, but occasionally upon the stem or upon the tendrils. 

 Although frequently a large number of eggs are thus found upon the 

 same leaf, the caterpillars are in no sense gregarious. On hatching 

 they almost invariably migrate to other leaves, and each one lives singly. 

 At first it feeds without concealment on the under surface of the leaf, 

 then it begins to draw the outer edges together by silken threads as a 

 sort of protection, apparently, from the daylight, as it feeds mainly at 

 night. The young larvre are dark colored and nearly black, but grow 

 lighter with successive molts. 



DIMORPHISM. 



Just as in the preceding species, a dimorphism occurs with the comma 

 butterfly. The hibernating form has been called harrisii and the sum 

 mer form dry as. The distinction between the two forms is not as 

 marked as with the preceding species, nor is the relegation to distinct 

 broods as marked. The fact which we have just noted may be called 

 simply the general rule. In its southern range the species is three 

 brooded, the first brood being composed of dryas, the second of both 

 forms, and the hibernating brood of harrisii only. 



NATURAL ENEMIES. 



This species is quite as extensively parasitized as is interrogationis. 

 Dr. J. B. Smith, after his experience in the hop fields in 1883, stated 

 that not one in ten of the insects ever reaches the butterfly state. The 

 chrysalids which he collected in the autumn were without exception 

 infested. The parasite which caused this great destruction of chi 

 lids in 1883 was Pteromalus vanessw. The only other hymenopterous 

 parasite found to affect this insect is Olypta erratica, which Dr. Riley 

 reared in Missouri from tlie chrysalis of the butterfly. Mr. Scudder also 

 states that he reared or had scut to him a tachinid fly raised from this 

 species, but the specimen has been lost, so that lie does not know the 

 locality or the species. 



Remedies. — Same as for preceding species. 



