October, ’20] 
WADLEY: SQUASH BUG 
419 
were reared in cloth-covered cages in the garden for total nymphal 
life. The periods in pot cage rearing are perhaps a little longer than 
normal, as the nymphs did not thrive as well as in the larger cages. 
Dr. Chittenden has found nymphal instars at Washington to require 
3, 8 or 9, 7 or 8, 6, and 8 days respectively, totalling 33 days. Weed 
and Conradi report that the instars require 3, 9, 8, 7 and 9 days re¬ 
spectively, with a total of 36 days, in New Hampshire. The figures 
secured at Wichita are given in Table II below. 
Table II.—Length of Instars 
July and early Aug., hot weather 
Late Aug. and Sept., cool, nights chilly 
Stage 
Number 
specimens 
Average 
length 
Variation 
Number 
specimens 
Average 
length 
Variation 
1st. 
14 
2.14 days 
6.2 days 
8.1 days 
(14) 
2 to 3 days 
4 to 8 days 
6 to 11 days 
5 
5.2 days 
9.25 days 
13 days 
10 days 
12 days 
49.45 days 
4 to 7 days 
8 to 11 days 
2nd. 
10 
4 
3rd. 
4 
1 
4th. 
(1) 
2 
9 to 11 days 
5th. 
1 
Total. 
Cloth covered 
30.44 
26 to 36 days 
46 to 56 days 
cages. 
28 to 30 
22 to 34 days 
One nymph reared in hot weather required fourteen days for the 
fourth and fifth stages combined, the fourth molt being overlooked. 
It can be seen that these two stages must cover fourteen days or less 
in summer if the length of the first three instars combined is compared 
with their average nymphal life. In October, with frosty nights, one 
nymph required twenty days for the fourth instar while another in the 
fifth instar lived seventeen days without molting. 
Seasonal History 
The squash bug in southern Kansas has, besides the first summer 
generation, a large, but not complete second' generation, and a small 
third generation. In east central Iowa there is a small second genera¬ 
tion but no third. The bugs increase rapidly during the active season, 
but this is short owing to their temperature requirements. There is 
probably a large or small second generation throughout the corn belt, 
and in the South three or more generations may be expected. The 
common statement that but one generation develops seems based on 
the work of Weed and Conradi in New Hampshire, which was accurate, 
but not representative for most of the country. Slingerland, Gillette, 
Sirrine, Smith and Garcia, have stated as their belief that more than 
one generation develops. 
Over-Wintered Generation. Only adults survive the winter in 
most of the United States, though it seems likely, from the tempera¬ 
ture nymphs endure in the fall, that they might winter successfully 
