DISPERSION OF GIPSY-MOTH LARViE BY THE WIND. 
9 
borne, however, by northeast and southeast winds from beach infes- 
tations 1 mile or more distant. This screen was inspected in May by 
Dr. Howard and Dr. Paul Marchal. 
Table II. — Dates and numbers of newly hatched caterpillars caught on screen,, with tem- 
peratures, direction of wind, and velocity of wind, at Salisbury Beach, Mass., in 1913. 
Date and time removed. 
Number of 
caterpil- 
lars caught. 
Maxi- 
mum 
temper- 
ature. 
Minimum 
tempera- 
ture. 
Average between 9 a. ra. 
and 5 p. m. 
Prevailing 
wind direc- 
tion. 
°F. 
May 8 
May 9, p. m 
May 10 
May 11, a. m 
Moy 12 
May 13 
May 14, a. m 
May lo, a. m. and p. m 
May 16, p. m 
May 17, p. m 
May 18 
May 19, p. m 
May 20, p. m 
May 21, p. m 
May 22 
May 23, p. m , . 
May 24 
May 25 
May 26, p. m 
May 27 
May 28 
May 23 
May 30, p. m 
May 31, p. m 
June 1, a. m. and p. m. 
June 2, p. m 
June 3, p. m 
June 4, p. m 
June 5, p. m 
Total 
(') 
C 1 ) 
( 2 ) 
S. and SE . . . 
W. andSW. 
NW 
NW 
NW.andSE 
SW 
NW 
W. and SW. 
NE 
E. and NE.. 
W. and NW 
NW.andW. 
SE 
E. to NW... 
NW., SW., 
and E. 
N. to E 
E . and SE . . 
NW to E . . . 
E 
NE 
NW 
W.andNW. 
NE to NW . 
SE to SW... 
NW 
SW 
NW. to E... 
E. to S 
No examination. 
No records. 
It will be noted from Table II that 266 caterpillars were caught on 
450 square feet of wire, and most of these on days when the winds 
blew from the northwest, west, or southwest, namely, May 14 to 19, 
May 15 to 17, May 19 to 25, May 20 to 30, etc., while fewer were 
caught when the wind was from the northeast and southeast. This 
may be explained by the light infestations 1 mile or more to the north- 
east and southeast; also it will be noted that winds from these direc- 
tions along the coast are accompanied by much lower temperatures, 
at which time the caterpillars spin less actively. 
Many of the small larvse were taken on the posts and crosspieces of 
the structure; thus of the 25 caught May 19, 18 had lodged in this 
manner and were living when removed. Others were swinging by 
threads on the east side of wire, where they had blown through the 
mesh from the west, the threads having caught in tanglefoot. 
96810°— Bull. 273—15 2 
