Lesser grain borer

(Rhyzopertha dominica)


The pronotum of the beetle, which is approximately 3 mm long and dark brown in colour, covers the head like a hood. The head is therefore hidden under the round pronotum; only the antennae, ending in a three-limbed club, are visible. The females lay their eggs loosely on grain kernels. The larvae and beetles feed on grains and leave bite holes in irregular shapes and different sizes. Older larvae bore into the kernels and pupate there. This type of beetle is primarily suited to higher temperatures and has come to us here in Germany from its home in the tropics and subtropics.

It cannot hibernate outside stored grains – its development stops at temperatures below 18 °C.




The lesser grain borer causes damage by feeding on grains, but also on grain products, baked goods, legumes, drugs and many more. When the nutritional substrate has been infested, it develops a honey-like odour. Furthermore, with its boring skills, the beetle can damage packaging material (boring holes).