Eight common insect pests - Rusty grain beetle

Rusty grain beetle

This beetle is the most serious pest of stored grain in most regions of Canada. It usually feeds on the germ, that is, the embryo, of a whole seed. Heavy infestations cause grain to spoil and heat.

Appearance and behaviour

The adult:

  • Is a flat, rectangular, shiny, reddish-brown beetle
  • Is 0.2 centimetres long
  • Has long, bead-shaped antennae that project forward in a V
  • Moves rapidly in warm grain and can fly when the air temperature is above 23°C.

Both the larvae and adults feed on the germ and on damaged kernels and wheat dust. The tiny larvae penetrate and feed on the germ of damaged kernels.


Complete development from egg to adult takes about 21 days when the temperature of the grain is 31°C and the moisture content is 14.5 percent. Each female is capable of laying 200 to 500 eggs, which are deposited loosely in the cracks of the grain kernels and in grain dust.

Rusty grain beetle image

dorsal view of the rusty grain beetle More on the rusty grain beetle
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