Yellow mealworm beetle

(Tenebrio molitor)

Adult: 12–18 mm
Larva: approx. 30 mm

Identification marks

A full grown mealworm beetle is quite large and black or dark brown in colour. It antennae are short, stocky and filamentous. Its elytrons have vertical grooves. It is similar to the destructive flour beetle, but larger.

Its larva is yellow-brown, shiny and has a hard shell. It has a stocky body and its back end has two small juts.


In nature, the mealworm inhabits decomposing trees and bird and wasp nests, and are brought into homes from outdoors. An adult beetle usually moves in the dark and thrives in slightly damp premises.

Mealworm larvae, or just mealworms, are grown to be used as food for caged birds and reptiles.


Both the worms and the beetles eat grain produce and also contaminate them. Flour becomes cloddy and starts to smell of mildew.

Prevention and extermination

Link to the extermination section