THE DISPEESIOX OF THE GIPSY MOTH. 27 
LABORATORY EXPERIMENTS. 
On May 3, 1911, 1,500 gipsy-moth caterpillars, 12 hours old or less, 
were placed in a glass battery jar, which in turn was placed for a 
short time in the laboratory yard where the temperature was 4G° F. 
There was no activity, and later, when the jar was placed in the 
basement where the temperature was 48° to 50° F., the same result 
was observed. The jar was then placed in the incubator and the 
following notes were made by Mr. Collins : 
The temperature was held at degrees mentioned for from 10 to 20 minutes. 
52° F. No motion unless larvae were disturbed; then it was very slight. 
54° F. No motion in mass of larvae. Two crawled 5 inches. 
56° F. No motion in mass of larvae. 
58° F. No motion in mass of larva?. Two have crawled 1 inch in 10 minutes. 
60° F. No motion in mass of larvae. Two have crawled 6 inches ; two. 4 
inches. 
62 D F. No motion in mass of larvae. Fifteen larvae crawling. One climbing 
up thread that had been spun. One spun 1 inch and crawled up. One spun 
* inch. 
64° F. Motion in mass noticeable. Fifty larvae crawled actively, a few spin- 
ning. 
66° F. Motion in mass more noticeable. One hundred larvae crawling, a few 
spinning short threads. 
68° F. Mass of larvae active. Eight larvae have each spun 7 A inches. 
70° F. Almost every larva moving. 
72° F. Caterpillars all crawling about and spreading freely. 
74° F. Many spinning and hanging by threads. 
76° F. Larvae very acthe and spinning. 
78° F. Half of the larvae have crawled from jar. All active. They spin 
rapidly. 
80° F. Active and spinning freely. 
84° F. About the same as S0° F. 
88° F. Possibly a little more active. 
92° F. Larvae crawling and spinning more rapidly. 
96° F. All caterpillars have left the jar and are on the move. It took this 
temperature to force all of them from the jar. 
100° F. Larvae very active. They crawl very fast, but spin little. 
106° F. Same as 100° F. 
108° F. Larvae gathered in masses ; less crawling and spinning. 
110° F. Little crawling; larvae squirming in the masses. 
Aftfer holding the temperature for two hours at 110° F. the incubator was 
cooled down to 82° F. Twenty-five dead larvae were found, and the remainder 
were not very active. The temperature was then raised again to 110° F. At 
92° F. larvae became more active, and this continued until 100° F. was reached. 
Most of them showed the effects of the previous high temperature. 
A set of observations was also made May 3, 1911, on first-stage 
caterpillars which hatched April 22 and were feeding in trays at the 
laboratory. No motion was noted at 54° F.,but when the temperature 
rose to 62° F. they crawled slowly about on the food. At 68° F. 
they were crawling freely, and activity increased as the temperature 
rose. 
