26 INSECTS INJURIOUS TO SUBTROPICAL FRUITS. 
Table I. — Length of the egg stage of Heliothrips rubrocinctus, Washuigton, D. C, 1912. 
Exueri- I Date of 
„3v' oviposi- 
mentNo.J ^ 
Eggs hatched on — 
Minimum 
length of 
stage. 
Maximum 
length of 
stage. 
Average 
mean tem- 
perature. 
1 
2 
Apr. 11 
Apr. 14 
Apr. 26(1) 
Days. 
15 
} « 
Days. 
°F. 
78.78 
/Apr. 29 (2) . . . . 
\Apr. 30(1) 
16 ,7.1 
] 
From leaves picked in Florida on April 3 the larvae continued to 
emerge until April 12, giving a minimum length in this case at Miami 
of at least nine days. 
The length of the egg stage was not determined by the writer for 
Florida. Urich found that on the island of Trinidad the eggs hatched 
for three days after they were picked and freed of the adults, but 
made no exact deteirnination on the length of incubation. The 
length of the egg stage in Florida will be very similar to that of 
JisemorrJioidalis, or from 8 days as a minimum to 16 or 17 days as a 
maximum as observed by the writer in the greenhouse. 
In the greenhouse a number of experiments were conducted and 
gave a length of the larval stage of from 8 to 16 days, with average 
mean temperatures of 68° to 76° F. (See Table II.) 
Table II. — Length of larval stage of Heliothrips rubrocinctus in greenhouse, Washington, 
D. C, 1912. 
\ 
Ex- 
peri- 
ment 
No. 
Date 
larvae 
hatched. 
assfSr 
Date last 
larva pu- 
pated. 
Number 
pu- 
pated. 
Minimum Maximum 
length of : length of 
stage. stage. 
Average 
mean tem- 
perature. 
1 
2 
3 
Apr. 3 
...do 
Apr. 6 
28 Apr. 11 
10 ...do 
6 | Apr. 17 
Apr. 18 
Apr. 13 
Apr. 22 
20 
6 
3 
Days. 
8 
8 
11 
Days. 
15 
10 
16 
o p 
68.88 
i 76. 08 
68.5 
i Records missing for first four days, but would probably not alter the average mean temperature more 
than a degree either way. 
In Trinidad the larval period requires six days for development. 
The temperatures were not stated, but were probably quite high, 
as the growth was very rapid. In Florida the larval period will 
probably occupy from 6 to 20 days, depending upon the tempera- 
ture and humidity. 
Urich found that the prepupal stage required one day and the 
pupal stage two days for development. During the month of 
November, with a moderately cool temperature, in a greenhouse, 
the writer found that the prepupal stage required from one to two 
days and the pupal stage from two to six days. 
A large number of prepupa?, under observation in the greenhouse 
in April, 1912, were found to require from one to four days for devel- 
