THE BLACKHEAD FIREWORM OF CRANBERRY. 
19 
32 males and 42 females of the first generation were collected from a 
cranberry bog on July 15, 1918, and immediately confined as follows 
in three battery jars 9 inches high by 5 inches wide: Jar No. 1 con- 
tained 12 males and 12 females; jar No. 2, 10 males and 12 females; 
jar No. 3, 10 males and 18 females. Each jar was provided with a 
few inches of slightly moist sand on the bottom, an abundance of 
clean cranberry uprights, and a sponge moistened with a weak solu- 
tion of sugar and water for food and moisture, 
Every 3 hours from 2 a. m. to 9 p. m. daily until July 20 the up- 
rights in each jar were replaced with fresh ones and the eggs on them 
and on the side of the j.ar counted and recorded. The sponge was 
also moistened daily. 
The number of eggs found deposited at each examination is sum- 
marized in Table 2. As will be noted therein, eggs were laid during 
every period between examinations, but the largest number of eggs 
was deposited between 3 p. m. and 9 p. m., 663, or 39.6 per cent of 
the total, being deposited between 3 and 6 p. m., and 650, or 38.8 per 
cent, between 6 and 9 p. m. The smallest numbers were deposited in 
the 12-hour period between 9 p. m. and 9 a. m. It will be noted fur- 
ther that the time of day during which eggs were deposited in largest 
numbers is also the period of greatest activity on the bog. 
Table 2. — Number of eggs of blackhead fireworm moth deposited every 3 hours 
from 6 a. m. to 9 p. m. by moths of the first generation confined in battery 
jars; Seaview, Wash., July 15 to 20, 1918. 
Period of deposition. 
Number 
of eggs 
deposited. 
Per cent 
of total 
deposited. 
• 
Period of deposition. 
Number 
of eggs 
deposited. 
Per cent 
of total 
deposited. 
9 p. m. to 6 a. m : 
78 
8 
67 
209 
4.6 
.5 
4.0 
12.5 
3 p. m. to 6 p. m 
663 
650 
39.6 
6 a. m. to 9 a. m 
6 p. m. to 9 p. m 
Total 
38.8 
12 noon to 3 p. m 
1,675- 
100.0 
The number of eggs found deposited at each examination is shown 
in graphic form in figure 10, together with a curve showing the hourly 
temperature during the period of the experiment. Attention is here 
drawn to the influence of the temperature on egg-laying. It will be 
noted that the largest number was deposited between 3 and 6 p. m. on 
July 16, a few hours after the highest temperature, namely, 75° F., 
was recorded. 
SEASONAL HISTORY. 
It was noted that larvae of the first generation appeared in greatest 
abundance on the bogs about the latter part of May, the pupae toward 
the middle of June, and the moths about the first or second week 
in July. 
