b INSECTS INJURIOUS TO SUBTROPICAL, FRUITS. 
LIFE CYCLE. 
In ascertaining the length of the life cycle the average lengths 
of egg, larval, and pupal stages were added together, and to this an 
additional 3 days, which was the usual time from the appearance of 
the adult female until ovipositing began. The life cyde thus in- 
cludes the period from egg to egg, or from the time the egg has left 
the abdomen of the female of one brood until the eggs of the next 
brood appear. 
Egg stage. — The length of the egg stage was determined by con- 
fining adult thrips on potted orange plants overnight, then remov- 
ing all insects and examining the plants twice daily, and counting 
the larvae hatched until they cease to appear. The length of the 
egg stage of 19 eggs during the month of August, 1909, was found 
to be 2^ days for a minimum and 8 days for a maximum, with an 
average of 6.2 days. Eggs deposited the latter part of September 
required from 20 to 24 days for incubation. During May, June, 
July, and August, 1910. observations on 45 eggs gave a minimum of 
5 days, a maximum of 13 da}^s. and an average of 8.1 days for 3 
months. It is probable that the majority of eggs deposited during 
May, June, July, and August would require from 6 to 8 days for 
incubation, while in March, April, September, and October the 
length of the egg stage would be considerably more. 
Larval stage. — The number of days required for the development 
of the larva varied from a minimum of 3 days to a maximum of 13 
days, with an average of 6.06 days for 55 individuals; and a mini- 
mum of 3 days, a maximum of 13 days, and an average of 7.2 days 
for 73 individuals during April, May, June, July, and August. The 
length of the larval stage would probably be extended, similar to the 
egg stage, during September and October. Two distinct larval 
stages were observed. The first stage is usually about two-thirds as 
long as the second, and the larvae more active. 
Pupal stage. — The pupal stage was best observed by keeping larvae 
in confinement until they pupated. The total length of the pupal 
instar for 30 individuals, under observation during June and July, 
1909, varied from 2 to 5 days, with an average of 3.6 days; while 
287 observations during April to August, 1910. gave a variation of 
2 to 7 clays, with an average of 1.8 days. Two pupal stages were 
observed, there being a distinct molt from the first to the second 
stage, which begins with a splitting of the skin from the head back 
dorsally to about 7 to 9 abdominal segments. The pupa? are more 
active in the first than in the second stage. 
Total life cycle. — The life cycle, obtained by adding the aver- 
age lengths of egg, larval, and pupal stages, and allowing 3 days 
