8 BULLETIN 250, U. S. DEPARTMENT OF AGRICULTURE. 



American Beech (Fagus grandifolia Ehrh.). 



Field observers all agree tbat gipsy-moth larvae feed heavily on tbis species 

 during tbe first tbree stages, after which they migrate to other species and 

 usually return to do considerable feeding during the last, or, in some cases, 

 a part of the last two stages. Tray experiments verified this, for in the first 

 three stages there was heavy feeding on the foliage, whereas in the fourth stage 

 there was much less feeding and larval growth was retarded. These cater- 

 pillars were restless and appeared to be searching for different food. They 

 died before reaching full growth. 



It is evident that the beech must be associated in a mixture with one or 

 more favored species in order that the gipss^ moth may reproduce normally. 



Black Birch (Betula lenta L.). 



Field observations indicate that feeding on the black birch is somewhat 

 variable, and it is seldom severely defoliated except in grossly infested areas. 



The results secured from the tray experiments were also variable, and while 

 it is possible for larvae in all stages to survive on this foliage, they usually do 

 not grow as rapidly or develop as vigorous individuals as when supplied with 

 more favored food. 



Apparently this tree comes near the line of favored and unfavored species. 



Gray Birch (Betula populifoHa Marsh.). 



This species is more generally distributed than any other in the area infested 

 by the gipsy moth. 



All the observers agree that the larvae feed on this birch through all stages 

 and grow large and rapidly except, possibly, in the first stage. Reproduction 

 of the moth on this tree is usually heavy. 



In the laboratories the larvae grew rapidly after the first stage and produced 

 many moths. 



One peculiarity was observed in the feeding of the larvae ; both at Worcester 

 and Melrose Highlands the young larvae fed almost wholly on the petioles of 

 the leaves, severing them from the blades. 



Several cases have been observed in the field where the bark on the tender 

 twigs has been completely girdled by the larger larvae. 



This is one of the most favored food plants of the gipsy moth. 



Paper Birch (Betula papyrifera Marsh.). 



This birch is found quite plentifully in the higher altitudes of the gipsy-moth 

 infestation, but in the low altitudes the species is represented by only a few 

 widely scattered specimens. 



In the field the larvae feed on this tree in all stages, and total defoliation 

 results if the infestation is sufficiently great. (PI. III. fig. 1.) 



In the tray work this species proved a very favored food. From one tray of 

 first-stage larvae at the Worcester laboratory, Mr. Wooldridge obtained _.". egg 

 masses. Heavy reproduction was also obtained at tbe Melrose laboratory. 



Red Birch (Betula nigra L.). 



This species occurs in a few localities in New England. Mr. Proctor, who 

 had trees under observation in the Merrimac Valley, reports feeding in all 

 stages and defoliation toward tbe end of the season. 



