34 
THE BEAN THEIPS. 
In these experiments the larvae were observed to feed for a period 
of 9 to 10 days and then to leave the plant to pupate, and 10 to 12 
days were required between hatching from the egg and changing to 
prepupse. 
During the year 1910 a number of larvae that hatched on July 28 
were observed to change to prepupa? on August 7, the total length 
of the larval stage being 10 days, with an average mean temperature 
of 72.1° F. 
The length of this stage later in the summer and in early fall 
for this locality unfortunately Avas not observed, but was probably 
somewhat shorter for August and September and considerably 
longer in October and Xovember. 
THE PREPUPA AND PUPA. 
As the prepupa and pupa are two distinct stages, although closely 
related, the length of each was separately determined. These two 
stages during the spring of 1911 required from 3 to 6 days for the 
prepupa and from 9 to 14 days for the pupa, or a total of from 14 
to 19 days. The results are shown in Table VIII, with the average 
mean temperature for each experiment. 
Table VIII. — Length of prepupal and pupal stages of the oean thrips at Comp- 
ton, Cal., during March to May, 1911. 
Exp 
No. 
Larvae changed to pre- 
pupa?. 
Prepupse 
changed to 
to pupae. 
Adults 
emerged. 
Length of stage. 
Average 
mean 
tempera- 
ture. 
Date - ber. 
Date. 
Num- 
ber. 
Date. 
Num- 
ber. 
puptl. P »P al - 
Total. 
1 
Mar. 31 
5 
1 
1 
2 
Apr. 3 
Apr. 15 
Apr. 25 
Apr. 29 
5 
1 
1 
1 
Apr. 17 
Apr. 24 
May 4 
May 10 
5 
1 
1 
1 
Days, i Days. 
3 j 14 
5 9 
Days. 
17 
14 
15 
16 
°F. 
59.2 
2 
Apr. 10 
59.5 
3 
4 
Apr. 19 
Apr. 24 
Total 
6 
5 
9 
11 
57.9 
56.9 
9 
8 

8 
In the month of July these stages required from 1 to 4 days for the 
prepupa, and from 4 to 7 days for the pupa, or a total of from 5 to 11 
days. The number that required less than 7 days, however, was very 
small. During this month the average mean temperature was 69° F. 
Table IX shows the results of these experiments and the average 
temperature for each. 
