74 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
bugs began to destroy them, coming in such extraordinary numbers as 
to occasion very general comment.” It may be that during a dry, hot 
August the nymphs also would cause serious loss, but within the writer’s 
experience plants which have escaped destruction by the adults are well 
able to support the nymphs, due to the tremendous mid-summer growth 
of cucurbits. 
Seasonal History 
The time during which the various stages in the life of the squash 
bug are present in Massachusetts is shown in the accompanying chart 
(fig. 2), which is a record of field observations during the seasons of 1920, 
1921, and 1922. In addition, the chart is of interest in its record of the 
year 1921. A glance at the chart will show that all stages were present 
in the fields for a shorter time than in the other two years, and that all 
bugs had left the fields at least a month before the first killing frost. 
This early completion of its seasonal activities seems best explained by 
the late fall of 1920 and the mild winter and early spring of 1921. These 
combined to cause a rapid emergence of the overwintered adults, and a 
subsequent concentration of oviposition in the latter part of June and 
early July. Since all nymphs had reached the fifth instar by September 
first, their development was not retarded by the cool September weather, 
as in average years. The fact that all adults had left the fields nearly 
a month before the vines were killed by frost seems to indicate that they 
normally do only a certain amount of feeding before seeking winter 
quarters. 
In 1921, as soon as the peculiarities of the season were evident, a close 
watch was kept on bugs in the field and on those in breeding cages as 
well, but no mating or egg laying by the newly developed bugs was ob¬ 
served. It seems safe to say, therefore, that there is never more than 
one generation of the squash bug each year in Massachusetts, for if it 
were possible for a partial second generation to develop, it would surely 
appear in such a season as that of 1921. 
Table 1. Length of Developmental Stages of Squash Bug, Amherst, Mass. 
Stage 
Number of 
Individuals 
Time 
days 
Average 
days 
Egg 
151 
11-16 
13.7 
1st instar 
86 
3- 4 
3.3 
2d instar 
85 
3-11 
6.6 
3d instar 
82 
4-13 
6.6 
4th instar 
63 
4- 9 
6.4 
5th instar 
59 
9-22 
16.6 
Total from egg to adult 34-75 days, average 53.2 days. 
Table 1 is a summary of breeding records obtained in life history cages. 
The variations exhibited are due in part to temperature differences, but 
