FOOD PLANTS OF THE GIPSY MOTH IN" AMERICA. 27 



Bay-leaved Willow {Salix pentandra L.). 



From trays started with first-stage larvae only fourth-stage larvae were pro- 

 duced before they all died. No adults were obtained until fifth-stage larva? were 

 started. The foliage was rather distasteful to them and growth was slow. 



No field observations were made on this species. 



Sandbar Willow (Salix ■interior Rowlee). 



Not as favored as the first two species, but more favored than the bay-leaved 

 willow. Trays started with third-stage larvae produced both male and female 

 moths. 



No field observations were made on this willow. 



Witch-hazel (Hamamelis virginiana L.). 



From the field came reports of the feeding of gipsy-moth larvae in all stages 

 upon this foliage, but probably more freely in the first stages. 



In the trays, adults were reared from first-stage larvae, which fed steadily in 

 all stages. 



The results given indicate in a general way the susceptibility of 

 the species concerned to gipsy-moth attack. 



There is in some cases, at least, considerable variation in suscepti- 

 bility of different trees of the same species. 



During the summer of 1912 foliage from two willow trees (Salix 

 alba L.) were tested in trays at Melrose Highlands. They were 

 growing side by side on lowland near a brook and both were in vigor- 

 ous condition. First-stage gipsy-moth larvae were placed in trays 

 on the foliage of each tree. 



Those supplied with the foliage of one tree fed normally, grew 

 rapidly, and in due time developed into large adults. The other lot 

 grew very slowly and the larvae were very small and small adults 

 developed. Nearly three times as many eggs were secured from the 

 first lot as from the second. All the larvae used in the experiment 

 hatched from the same egg cluster. 



In 1913 foliage from the same trees and larvae hatched from the 

 eggs of the previous year were used and the results were exactly 

 reversed. 



This indicates that there is variation in results with the same spe- 

 cies of tree, but in this case it was not constant. A number of experi- 

 ments along this line are contemplated. 



COMBINATION-TRAY EXPERIMENTS. 



Several series have been conducted to determine feeding prefer- 

 ences of gipsy-moth larvae when two species of foliage were supplied 

 in the same tray. In deciding the combination of species to be used 

 it was thought best to place in the trays species that are usually found 

 growing together in the field. 



