FOOD PLANTS OF THE GIPSY MOTH IN AMERICA. 29 



Gkay Bikch and White Pine. 



The larvae fed freely in all stages on gray birch, but none at all on the pine 

 in the first stage. The feeding on the latter species gradually increased until, 

 in the last stages, they fed as well on this foliage as on the birch. They grew 

 well and attained normal size and several reached the adult stage. 



In the field in areas having this combination, the larvae fed on the birch 

 during the first three stages, when they attacked the pines. These were de- 

 foliated in many cases in the last three stages. The prevalence of wilt in the 

 field often exerts a powerful influence in preventing complete defoliation of 

 pine when it is grown in this combination. 



Gray Bikch and Red Spruce. 



During the first stage all of the feeding was on the gray birch. There was 

 a slight increase in feeding on the spruce in the later stages until the last two, 

 when it diminished on the spruce. 



The larvae were rather small in size and grew slowly. A few reached the 

 adult stage. 



Paper Birch and Hemlock. 



The larvse fed freely on the paper birch in all stages. No feeding was noted 

 on hemlock in the first stage, light in the second, and increasing during the 

 third, and continuing moderate until the trays were closed. The larvae showed 

 a preference for birch in all stages, grew steadily to large size, and a large 

 number of male and female moths developed. 



Paper Birch and Sugar Maple. 



The sugar maple in combination with this species is a favorable food. The 

 larvae fed upon it freely from the first to the fifth stages. During the fifth 

 and sixth stages it was eaten more moderately. Birch was eaten freely at all 

 times, although preferred in the later stages. Both species were eaten equally 

 in the earlier stages. 



The larvae were of medium size and several reached the adult stage. 



Paper Birch and Large-toothed Aspen. 



Both of these foods are favorable. Except in the first stage, when the poplar 

 was preferred, the larvae fed with the same degree of freedom upon each. They 

 grew steadily in the first stage, but more rapidly in the remaining stages, and 

 attained average size. Several developed into adults. 



Paper Birch and Red Spruce. 



Larvae fed freely on the birch in all stages, but did not feed on the spruce in 

 the first stage. Feeding increased from the beginning of the second stage to 

 the end of the fifth. Medium-sized larvae resulted, from which several adults 

 developed. 



Paper Birch and Witch-hazel. 



The larvae fed freely on both food plants, with slight preference for witch- 

 hazel until near the end of the experiment, when birch was eaten more freely. 

 Large larvae resulted, from which several adults developed. 



