8 
BULLETIN 273, U. S. DEPARTMENT OF AGRICULTURE. 
ing was completed. In 1914 there was an abnormally late spring, 
which shortened the hatching season, and wind dispersion was noted 
about one week after the first date and continued about the same 
period after the last was observed. The total period over which 
windspread may be expected is from 27 to 30 days in a normal 
spring, and from 18 to 20 days during a late spring. Ordmarily the 
maximum dispersion is effected during 10 to 15 days of high tempera- 
tures and favorable winds. 
LONGEVITY OF FIRST-STAGE LARVAE AFTER BECOMING ENTRAPPED IN 
TANGLEFOOT. 
In connection with the experiments conducted by using tanglefoot 
on screens to catch caterpillars blown by the wind, it became essential 
to know about how long they would live after becoming entangled. 
As a test, tanglefoot was smeared at various depths on heavy paper 
and 100 caterpillars dropped into these. Examinations were made 
at intervals from the time the experiment was started, and it was 
noted that after three hours practically all- were living; after six 
hours only two were attempting to move, and these were in a very 
thin smear. After eight hours 65 were dead, and 35 showed signs of 
life when disturbed. The following morning, after 24 hours, all were 
dead except seven, and these were in very thin smears, which had 
little effect upon them. 
The length of life depended upon the density of the tanglefoot in 
which they were placed. If the caterpillars in attempting to free 
themselves became submerged below the spiracles, which often hap- 
pened in 3 to 5 hours, they died shortly after. As a result, cater- 
pillars lodged in globules of tanglefoot on the screens died in 4 to 6 
hours, while those in very thin spots lived 24 or more. 
SCREEN EXPERIMENTS AT SALISBURY BEACH, MASS., IN 1913. 
April 24, 1913, a large screen (PI. Ill, fig. 1), as described, was 
erected on the edge of the marsh area near the beach, on a site which 
was 1 mile distant from infested woodlands to the northwest, 1J 
miles to the west, and 2\ miles to the southwest, The area to the 
east, composed of sand dunes, contained small amounts of vegetation, 
on which gipsy moths could thrive, but this was properly scouted 
and cleaned for an experiment on reinfestation by the wind. 
The temperature, wind direction, and wind velocity were taken 
each day at alternate hours from 9 a. m. to 5 p. m., and the screen 
was examined most days when the winds were fair for windspread 
from the west. Mr. F. W. Graham was in attendance at this screen 
and made many of the following observations and notes. 
No larvse were blown on the screen, which was one-fifth mile from 
the ocean, by winds coming directly from the east, Larvse were 
