THE GIPSY MOTH ON CRANBERRY BOGS. 7 
As a result of these observations it will be seen that the time of 
greatest dispersion follows from 13 to 14 days after hatching. It 
should be noted, however, that on uplands independent observations 
have shown that this period is shorter. 
With the exception of the year 1917, the woodland surrounding 
Muddy Pond Bog was lightly infested with the gipsy moth. Dur- 
ing that year there were a few scattered pockets on the western edge 
of the bog where a medium infestation existed. No heavy infesta- 
tions were noted during the years that these experiments were con- 
ducted. The results of the observations for 1917 may therefore be 
taken as illustrating what might reasonably be expected in any sim- 
ilar infestation, and are given in detail in Table 2. 
Table 2. — Trap record for the season of 1917 giving the total number of 'gipsy 
moth larvas taken from each trap and total for each day of dispersion, Muddy 
Pond Bog, Carver, Mass. 
Trap No. 
May. 
June. 
Total. 
26 
31 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
14 
1 

4 
3 
0) 
16 
11 
5 
4 
C 1 ) 
C 1 ) 
C 1 ) 
11 
15 
4 
3 
12 
10 
{ l 
17 
9 
4 
12 
11 
22 
28 
12 
3 
* 24 
0) 
C 1 ) 
C 1 ) 
169 
86 
58 
8 
43 
38 
11 
135 
149 
47 
8 
8 
( x ) 
46 
54 
20 
3 
35 
8 
10 
10 
11 
3 

0) 
0) 
C 1 ) 
10 
4 
2 

3 
2 
1 
4 
5 
1 


0)- 
0) 
2 
2 
2 

4 
0) 
C 1 ) 
7 
7 
3 

C 1 ) 
ft 
1 

2 
54 
2 
113 
3... 
80 
4 
44 
7 
8 
465 
373 
9 
159 
Total... 
39 
34 
77 
92 
337 
431 
136 
80 
16 
16 
6 
21 
3 
1,288 
1 No examinations made. 
From Table 2 it will be noted that the largest numbers of larvae 
were taken from the traps nearest the border of the bog, the number 
gradually diminishing as the distance from the border increased. 
It is interesting to note the results secured on the two vertical 
traps. On No. 10, which was constructed of wall board, 255 larvse 
were caught, while on No. 11, which was a wire trap, only 121 were 
secured. As these two traps were placed in equally favorable loca- 
tions, it is evident that many larvse passed through the wire screen. 
It is probable that wire treated with commercial sticky tree-banding 
material but having one- fourth-inch mesh would be much more effec- 
tive. It is also interesting to note the difference between the number 
of larvse taken on horizontal trap No. 9 and vertical trap No. 10. 
They had the same number of square feet of surface exposed, and 
although they were located near together, 159 were taken on the 
former and 255 on the latter. This shows conclusively that the num- 
ber of wind-borne larvse caught on a vertical surface is not a fair 
index of the number that will drop on a horizontal area of the same 
size. The density of infestation on low vegetation, when insects are 
