38 
THE BEAN THEIPS. 
Table XI. — Length of incubation of the eggs of the bean thrips, El Centro, 
Gal., 1910. 
Date of opposition. 
Number 
laid. 
Eggs hatched. 
Length 
of stage. 
Average 
mean 
Date. 
Number. 
tempera- 
ture. 
Julv 27 
2 
( 2 ) 
( 2 ) 
Aug. 1 
Aug. 15 
Sept. 6 
2 
1 
20 
Days. 
4§ 
4 
5 
°F. 
C 1 ) 
3 87.1 
Aug. 11 
Aug. 31 
3 88. 7 
1 Records missing. 
LARVAL 
Many. 
PERIOD. 
3 
At Brawley. 
The active feeding larva molts once before its final molt to the 
prepupal stage. This occurs in from one and one-half to two days 
after it hatches from the egg. The larva becomes full grown and 
changes to the prepupa in from four and one-half to five days. As 
might be expected from the great difference in the incubation period 
of the egg. the larval period in the Imperial Valley, as observed by 
Mr. Wildermuth, is much shorter than at Compton. These data 
are given in Table XII. 
Table XII. — Length of larval stage of the bean thrips at El Centro, Cal. 
during 1910. 
Exp. 
No. 
Eggs hatched. 
Molted. 
Changed to 
prepupa. 
Length. 
Average 
mean 
temper- 
ature. 
Date. 
Number. 
Date. 
Number. 
Date. ! Number. 
1 
2 
3 
Aug. 15 
Aug. 18 
Aug. 26 
1 
3 
1 
1 
1 
Aug. 16 
Aug. 19 
Aug. 28 
Sept. 3 
Sept. 24 
1 
1 
1 
1 
1 
Aug. 19 
Aug. 22 
Aue. 31 
Sept. 5 
1 
1 
1 
1 
Days. 
4§ 
% 
5h 
4 
5 
°F. 
85.8 
C 1 ) 
91.9 
4 
Sept. 1 
89.7 
Sept. 22.. 
Sept, 27 
81.8 
Total 
7 
5 
5 
1 Records missing. 
PREPUPAL AND PUPAL PERIODS. 
Unfortunately Mr. Wildermuth 's records give a very small amount 
of data on the length of the prepupal and pupal periods, but in the 
six examples observed (see Table XIII) the stages varied from 2 
to 3 days. "While the writer was studying the greenhouse thrips 
the prepupal stage was often observed to last only a few hours, and 
this same condition probably occurs with the present species in the 
high temperature of the Imperial Valley. 
