DISPERSION OF GIPSY-MOTH LARViE BY THE WIND. 
11 
In all 96 larvae were trapped during the season, most of which 
were removed on days when the wind blew from the west, southwest, 
or northwest. The largest catch was removed May 21, at which time 
the wind blew from the northeast and southeast, but it was evident 
that most of the larvae were caught May 20 in the afternoon, as the 
screen was not examined during that period. There was less source 
of spread from the northeast and southeast along the ocean shore 
than from the westward points. On May 21 the temperature ranged 
from 53° to 60° F., at which time there was reasonable activity among 
the caterpillars. 
One should not fail to note that spread was secured from all direc- 
tions from which the wind blew except from the east, and the in- 
festation at this point Was almost obliterated. No north winds 
were noted during the hourly observation periods. 
SCREEN EXPERIMENT CONDUCTED ON PLUM ISLAND, MASS., IN 1914. 
April 14, 1914, a screen (PL III, fig. 2) was erected on the edge 
of the marsh near the Merrimac River. It was of the same size and 
proportions as that erected 1 mile farther north, at Salisbury Beach. 
The shrubbery, composed mostly of beach plum, bayberry, wild rose, 
sumac, poplar, and willow, on the north end of the island, was ex- 
amined for egg clusters and these were creosoted. This practically 
obliterated the source of infestation to the eastward of the screen. 
The location of the screen (PI. Ill, fig. 2) was such that it was 2 
miles from infested woodlands across the marshes and Merrimac 
River to the northwest, west, and southwest. Frequent examina- 
tions made it possible to determine the direction from which all the 
caterpillars came. It is not supposed that all the caterpillars caught 
during the time west winds prevailed came from the nearest infesta- 
tions (2 miles), but in some instances 5 miles or more. There was, 
however, a small infestation on a few roadside willows 1 mile to the 
southwest, but these were so thoroughly cleaned and tanglefooted 
in the spring that no caterpillars could be found on them during the 
dispersion season. The woodland infestation was 1 mile beyond 
this, totaling 2 miles from the screen. 
Mr. C. E. Hood attended the screen, making three or four exami- 
nations for larvae daily from May 10 to June 13. The temperature, 
wind direction, and wind velocity were recorded hourly each day 
from 8 a. m. to 5 p. m., inclusive. 
