6 
BULLETIN 1093, U. S. DEPARTMENT OF AGRICULTURE. 
Finally, the whole surface was covered with a coating of com- 
mercial sticky tree-banding material about one- fourth inch in thick- 
ness to serve as a trap for the caterpillars. 
Later, improvements were made by setting the traps practically 
level, with an additional center support running longitudinally and 
serving as a ridge, which gave a slight pitch to either side, forming 
a perfect watershed. They were also raised to stand about 2 feet 
above the bog surface, particularly to facilitate inspection. 
No. 10, the solid-surface vertical trap, was constructed of wall 
board, with the upper edge of the trap 9 feet above the surface of 
the bog. Twelve 8-inch holes were cut through the wall board and 
covered with J-inch mesh wire screen in order to reduce the force 
of the wind, but more particularly to prevent a cushion of air from 
forming in front of the trap. The whole surface, wall board and 
wire, was given a coating of commercial sticky tree-banding material 
as in the case of the horizontal traps. (PL III, Fig. 1.) Trap No. 11 
was constructed in the same manner as No. 10, with the exception that 
three-fourths inch mesh wire netting was used for a surface. (PL 
III, Fig. 2.) All traps, with the exception of Nos. 10 and 11, were 
erected with the longer dimensions running east and west. Nos. 10 
and 11 were erected vertically, facing east and west. In order to 
obtain information regarding the number of caterpillars and how far 
they were blown onto the bog, these traps were located at varying 
distances from the bog border. 
RECORD OF TRAP OBSERVATIONS. 
Trap observations have yielded information in regard to the num- 
ber of caterpillars carried by the wind and as to the conditions under 
which they are carried. 
The time of hatching the gipsy moth caterpillars is governed 
by the temperature. It is evident that in order to control infestations 
on bogs careful attention must be given to this factor. ( See Table 1. ) 
Table 1. — The variation of time in hatching and dispersion of gipsy moth 
caterpillars during the period covered by observations at Muddy Pond Bog, 
Carver, Mass. 
Year. 
First 
hatching 
noted. 
First 
larvae 
taken on 
traps. 
Time of maxi- 
mum dispersion 
on traps. 
Time be- 
tween first 
hatching 
and maxi- 
mum dis- 
persion . 
Time be- 
tween first 
trap record 
and maxi- 
mum dis- 
persion. 
1916 
May 9 
19 
7 
6 
May 22 
26 
10 
15 
May 25-26 
Days. 
16-17 
1 .->- 1 7 
8-9 
12-14 
Days. 
3-4 
8-10 
5-6 
3-5 
1917 
June 3,4,5 
1918 
1919 
May 18, 19/26 ..... 
