8 BULLETIN 250, U. S. DEPARTMENT OF AGRICULTURE. 
AMERICAN BEECH (Fagus grandifolia Ehrh.). a 
Field observers all agree that gipsy-moth larve feed heavily on this species 
during the first three 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 eater- 
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 gipsy moth may reproduce normally. 
Biack Bircu (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 larve 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 Bircn (Betula populifolia Marsh.). 
This species is more generally distributed than any other in the area infested 
by the gipsy moth. 
All the observers agree that the larve feed on this birch rotons 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 larvee grew rapidly after the first stage and produced 
many moths. 
One peculiarity was observed in the feeding of the larve; both at Worcester 
and Melrose Highlands the young larve 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 larve. 
This is one of the most favored food plants of the gipsy moth. 
PAPER BrrcoH (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 larve feed on this tree in all stages, and total defoliation 
results if the infestation is sufficiently great. (Pl. III, fig. 1.) 
In the tray work this species proved a very favored food. From one tray of 
first-stage larve at the Worcester laboratory, Mr. Wooldridge obtained 25 egg 
masses. Heavy reproduction was also obtained at the Melrose laboratory. 
Rep Bircu (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 the end of the season. 
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