Mealworm Beetle Larvae (Tenebrio molitor)
Biology: The gleaming black-brown mealworm beetle is among the largest stored product pests with a body length of 13 to 18 mm. It occurs in bakeries, storehouses and flour mills, but also in human habitations, pigeon lofts and outdoors, especially in birds’ nests. The larvae grow to a length of 28 mm, are yellow-brown and are the “mealworms” used as feed for fish, reptiles and birds. Both larvae and beetles feed on flour and other grain products as well as many other products derived from animals and plants.
Damage: Larvae and beetles cause feeding damage and contamination damage to the affected products. The larvae also occasionally bore holes in rotten wood. With its long life cycle, this species does not generally tend to mass outbreaks, so that thorough cleaning and elimination of food residues should be sufficient to prevent a serious infestation.