6 Farmers’ Bulletin 1156. 
continuously, first to 
gnaw its way into 
the seed and then 
to eat out the con- 
tents of the seeds 
to secure nourish- 
ment for its growth 
and to make the 
circular opening 
moth itself emerges 
from the seed. The 
circular opening is 
not cut until the 
larva has become 
full grown. It then 
eats out a channel 
to the outside of the 
seed, leaving the 
Tig. 3—An ear of corn badly damaged by the Angoumois merest film of the 
grain moth, broken in two to show how perfect the ] ° t : tact 
kernels may appear when viewed from the side. see coa imtact. 
The moth is strong 
enough to push off this “cap” when it leaves the seed. The open- 
ing is often called the emergence hole. 
TIME REQUIRED FOR DEVELOPMENT. 
Under ordinary atmospheric conditions, temperature has every- 
thing to do with the development of the Angoumois grain moth. All 
eggs, larvee, pupe, and adult moths are killed if the grain is heated 
throughout to a temperature of 120° F. Exposure of the eggs to a 
temperature of 1° IF. for 24 hours has prevented their hatching. 
Ordinary winter storage temperatures below 60° F. in regions where 
the moth is a real pest will hold the moth in a quiescent or dormant 
state, but will not kill. Development goes on slowly between 60° and 
70° F., and very rapidly between 70° and 95° F. It does not matter 
whether these temperatures obtain indoors or out of doors. This ex- 
plains how the Angoumois grain moth can breed generation after 
generation in warehouses or rooms kept at a moderately high tem- 
perature in a cold climate with outdoor temperatures too low for 
the moth. 
Experimental work has not determined the developmental period 
of the Angoumois grain moth for various temperatures. The eggs 
will hatch during the heat of summer in from 7 to 10 days. Eggs 
may not hatch in colder weather in 3 or 4 weeks. In general, the 
through which the: 
