Continued
Lifecycle:
The egg, larva, and pupa stages of both weevils occur in the grain kernels and are rarely seen. Feeding is done within the grain kernel, and adults cut exit holes to emerge. Emergence holes of the granary weevil are larger than those of the rice weevil, and tend to be more ragged than smooth and round. Females drill a tiny hole in the grain kernel, deposit an egg in the cavity, then plug the hole with a gelatinous secretion. The egg hatches into a young larva which bores toward the center of the kernel, feeds, grows, and pupates there. New adults bore emergence holes from the inside, then leave to mate and begin a new generation. See the picture below of weevils as they emerge.

Female grain weevils lay from 36 to 254 eggs at a rate of 2-3 a day. At 80 to 86°F, 75 to 90% relative humidity, eggs hatch in wheat with a moisture content of 13.5 to 19.6% in 3 days. Larvae mature in 18 days, and the pupa in 6 days. The life cycle is about 30 to 40 days during the summer, and 123 to 148 days during the winter, depending on temperature. Adults live 7 to 8 months. Female rice weevils lay between 300 to 400 eggs, with the life cycle requiring about 32 days for completion. Rice weevil adults live 3 to 6 months, infesting grain in the field, especially in the tropics and sub-tropics, in fact it is one of the most serious pests. Two larvae can develop in one wheat kernel, but only one larva of the granary weevil can develop per wheat kernel. Both granary and rice weevils feign death by drawing up their legs close to the body, falling, and remaining silent when disturbed.

Again the treatment is the same for all stored product insects: