EXPEEIMENTS AT LINCOLN, MASS. 17 
it was very difficult to determine how far they might be carried 
under such conditions, owing to the small size of the rooms where 
the experiment was tried, it was possible in a few cases to secure 
specimens which had drifted from 20 to 30 feet from the fan. This 
led to an attempt to test the matter under outdoor conditions. 
Arrangements were made with Mr. L. H. Worthier, then assistant 
forester of Massachusetts, whereby the tests would be made coopera- 
tively Avith the department which he represented. Supplies and 
assistance were furnished by the State, and several men employed by 
the Bureau of Entomology attended to certain parts of the work. 
Many valuable suggestions were secured from Mr. Worthley, and 
from Messrs. D. M. Sogers and W. F. Fiske of this bureau. In carry- 
ing on the tests especial credit is due to Mr. C. W. Collins, who 
assisted in many of the experiments ; to Messrs E. A. Proctor, J. V. 
Schatfner, and K. W. Brown for assistance and suggestions; to Mr. 
H. K. Gooch, who constructed the screens and apparatus used; to 
Messrs. C. W. Stockwell, F. H. Mosher, and John E. Dudley, jr.. for 
helpful suggestions and for recording data on several phases of the 
work; and to Messrs. H. S. Barber, Melvin Guptill, H. A. Preston, 
and W. N. Dovener, who prepared the photographs and accompany- 
ing illustrations. Suggestions which had a practical bearing upon 
the tests were made by those mentioned and by many others con- 
nected with the work at the parasite laboratory, so that all have 
contributed to the results which will be given. 
For the weather conditions in Massachusetts we are indebted to 
Mr. J. W. Smith, district forecaster of the Weather Bureau, United 
States Department of Agriculture, at the Boston office. Data have 
also been secured from local forecaster Edward P. Jones, at Portland, 
Me., and from local forecaster E. C Vose, at Concord, X. H., who 
have very courteously allowed the records of their offices to be freely 
used. 
Plans were made to carry on several experiments out of doors as 
soon as the caterpillars began to hatch, and for this purpose a num- 
ber of favorably situated localities were selected. In each case a 
screen of galvanized-iron wire was attached to a wooden frame, and 
after the netting had been treated with a thin application of tree 
tanglefoot it was set up so that caterpillars were likely to drift upon 
it if carried by the prevailing wind. 
EXPERIMENTS AT LINCOLN, MASS. 
The first trap was placed on a raft (PL VI) which was moored 
near the center of Sandy Pond, Lincoln, Mass. Two screens, each 19 
feet long and 6 feet high, were placed at right angles so, as to form 
a cross. The screen used was ordinary poultry wire having a mesh 
about 1 inch in diameter. The woodland surrounding this pond was 
60474° Bull. 119— 13 2 
