Pests of Stored Grains

Pests of Stored Grains, There are different types of pests feeding on the stored grains and thus damaging them. Important examples of such pests of the stored grain are; rice weevils and flour beetles.

  1. Rice weevil:

The biological name of rice weevil is Sitophilus oryzae. They were given this name for the first time by Lineous.

The Sitophilus oryzae belong to the order coleoptera. Their wings are called elytera which are very tough. It is one of the most destructive pest of the stored grains. They destroy the grains more as both the larvae and adult feed on the grains.

The larvae bore the grain and feed on the central part of the grain, which is called carmal. While the adult feed on the whole grain. The larvae of Sitophilus oryzae are called grub.

Life history:

Colour and size:

Their colour is reddish brown. They are as small as 3.5 millimeters.


The female lays the eggs inside the grain. The colour of the egg is white and hatch in about 3 to 4 days. The hatchling larvae have no legs and are white in colour. In about 3 to 4 weeks, the larvae becomes pupae and then after 6 days or a week the pupae becomes adult. Then the adults mate and a new family arises. This total life cycle takes 4 to 7 weeks to complete.

  1. Flour beetles:

The biological name of flour beetle is Tribolium castaneum. They belong to the order coleoptera. They are commonly called as rust flour beetle also, this name is given to them because of their red colour.

When the infestation- a process when a pest attack on any product, occurs the wheat/ flour becomes yellowish in appearance. This occurs due to their reproduction cycle.

Both the adult and larvae damage the flour/ wheat.

Life history:

Colour and size:

The flour beetles are reddish in colour, that’s why they are also called rust flour beetles (as mentioned above).

They are 3.5 millimeters long.


The female lays about 400 to 500 eggs. The eggs are sticky and thus form a cluster by sticking to each other. These are white in colour. After 12 days, a small whitish brown larvae hatch from the eggs which then pupate in about 90 days. The pupae are also whitish in colour.

In about 1 to 2 weeks the pupae becomes adults. The adults are also called imego which then live for about 6 weeks, forming a new family and continuing their life cycle.

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