Presence of insects in indicated by the presence of webs, cocoons, dead or living insects and the presence of rodents is indicated by presence of holes in the bags containing food grains.
Fumigants are used to control the population of insects. These chemicals quickly vaporize and kill the insects without affecting the grain. In this method, the fumigant is placed in the storage structure infested by insects. The structure is made reasonably air tight and left undisturbed for a week. The fumigant vaporizes immediately and the vapors thus produced, kill the insects present in the food grains.
The rats are killed by use of certain poisonous chemicals called rodenticides. The rat poison is kept in the form of “baits” at a number of places in the godown. The rats eat these poison containing baits and die.