6 BULLETIN 250, U. S. DEPARTMENT OF AGRICULTURE. 
In the following pages are given a brief statement of the results 
secured with each food plant tested. Field observations are also 
included to make the data as reliable as possible. Experience has 
shown that results, even with the same food plant, vary to some extent 
during different years; and as the information is based upon three 
years’ work, it is believed that this variability has been given due 
consideration. 
Tt should be remembered that in the trays the larve were furnished 
with the same species of foliage during the entire season, hence the 
results are not exactly the same as would be secured under field con- 
ditions where a variety of food is usually available. A certain 
amount of injury to caterpillars always results from handling them 
in trays, so that the rate of reproduction in the experiments is in all 
cases less than under field conditions. : 
ALDER, SPRECKLED (Alnus meana [L.] Willd.). 
In the tray experiments the larve fed freely in all stages. The growth and 
reproduction were normal. The field observers agree that gipsy-moth larvz 
usually feed in all stages on this plant, but in the first three stages it seems to 
be preferred. As alder is of little commercial value it should be removed when 
cuttings are being made. (PI. III, fig. 2.) 
APPLE (Pyrus malus L.). 
This species was found to be a favorite food of gipsy-moth larvz both in the 
field and in the trays. In combination with other growth it is usually the most 
heavily infested. : 
Old trees of this species that have been neglected nearly always contain holes 
and crevices in which the gipsy-moth larve hide and go through their trans- 
formations, the females depositing their eggs where it is difficult to find them. 
These trees are a menace to the surrounding growth and should be removed. 
ARBOR VITZ (Thuja occidentalis L.). 
No observations were made on this species in the field, but it has been thor- 
oughly tested in the laboratory. No reproduction was secured until experiments 
were carried on with third-stage larve. The feeding was slight and develop- 
ment was slow and imperfect. It is an unfavored food. 
This species can be left in a stand of trees without fear of injury by the 
gipsy moth. 
Biack ASH (Frazinus nigra [Marsh.]). 
One adult male was reared from 100 lary started in the third stage. Many 
other tests were less favorable to the insect. Mr. T. J. Kennedy, one of the field 
observers, reports no feeding on this species of ash in southern New Hampshire. 
It is an unfavored species. 
BLur ASH (Frazinus quadrangulata Michx.). 
A single specimen of this tree was under observation. It was located in 
Elm Park, Worcester, and foliage was tested in the trays in the Worcester 
laboratory by Mr. Collins in 1912. 
Although larvee from the first to the fifth stages, inclusive, were tried, none 
reached the adult stage. It is an unfavored species. 
