FOOD PLANTS OF THE GIPSY MOTH IN AMERICA, 5) 
ously throughout the feeding season. It required the services of five 
assistants to attend properly to the feeding work and to record the 
necessary data. In addition, two assistants were employed to collect 
the food plants that were used in these experiments. Some of the 
species could not be secured in Melrose, and in a number of cases con- 
siderable travel was necessary in order to supply the foliage for the 
tests. During the summer of 1914 an assistant provided with a 
motorcycle was able to collect most of the foliage. 
About the same number of assistants was required to conduct the 
experiments at the sublaboratory at Worcester, Mass., during the 
summers of 1912 and 1918. 
A few tests or field observations were made on European trees and 
shrubs which oceur in New England, but no effort has been made in 
this report to consider the food plants of the gipsy moth in Europe. 
DIFFICULTIES IN CONDUCTING THE EXPERIMENTS. 
Asa result of previous experience in feeding caterpillars, it seemed 
necessary to secure a better method than simply placing leaves or 
twigs with foliage in the trays. When this is done the leaves wither 
rapidly in warm weather and often become so dry that it is extremely 
difficult to find all the first-stage caterpillars when the trays are 
cleaned. The use of the bottles of water in the trays obviated this 
trouble to a great extent and made the cleaning of the trays relatively 
easy. There were several kinds of foliage, such as linden, sassafras, 
and young growth of hickory, walnut, etc., that wilted rapidly in 
spite of every precaution that was taken. 
_ In most of the trays a considerable number of caterpillars died 
from the disease known as “ wilt,” and in a few cases the imported 
parasites produced heavy mortality among the gipsy-moth larvee. 
These factors operated in varying degrees during different seasons, 
but had an important bearing on the number of larve that survived 
the tests. 
FOOD PLANTS TESTED. 
Nore.—The writer expresses his appreciation to all who have assisted in these 
experiments. Special thanks are due to the Board of Park Commissioners of 
Worcester for the use of the sublaboratory in their city and to Mr. A. V. Parker, 
superintendent of parks, and Mr. H. L. Neale, city forester, for many courtesies 
extended; to Dr. C. S. Sargent and his assistants for permission to secure 
foliage at the Arnold Arboretum for some of the experiments; and to Mr. H. A. 
- Preston for preparing the photographs illustrating this report, as well as to 
the many other employees of the Gipsy Moth Laboratory who have contributed 
toward the data summarized in this report. 
1 The botanical designations, both scientific and common names, herein cited are verified 
by Britton and Brown, Illustrated Flora of the Northern States and Canada. Second 
Edition, Vols. I-III, New York, 1918. 
