Eight common insect pests - Yellow mealworm

Yellow mealworm

These insects are the largest found in stored grain. They are not common pests on farms. They infest animal feed and stored grain that is going out of condition.

Appearance and behaviour

The adult:

  • Is a black beetle about 1.5 centimetres long

The larvae:

  • Are yellow and 0.2 to 2.8 centimetres long

Yellow mealworms prefer dark, damp places in a granary or a feed bin. Because of their relatively large size, they are easily visible and often appear to be more numerous than they actually are. Their presence indicates poor storage conditions.


The adult lives for several months. Under harsh conditions, the larvae may take one to two years to change into pupae.

Yellow mealworm image

Dorsal view of the Yellow mealworm More on the yellow mealworm
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