Tenebrio obscurus F.
Secondary pest: Grain feeder
- Adults are similar in appearance to the yellow mealworm, but are often lighter brown in colour.
- Adults are long (12 to 18 mm).
- Dark mealworms may be distinguished from the yellow mealworm by the presence of more dense punctures on the head and pronotum than are present on the yellow mealworm.
- Larvae are cylindrical and move readily through the commodity.
- Larvae are initially white, but darken as they mature and reach a length of 25 to 30 mm.
- Yellow mealworm (Tenebrio molitor)
- Prefers to feed on grain and milled products that are damp and decaying and have been left undisturbed for some time
- Will also feed on sound food items such as meal, flour, bran, grain, coarse cereals, crackers, meat scraps, feathers, dead insects
Signs of infestation
- Larvae and adults are large and readily visible.
- Odours from out-of-condition grain are often noticed before presence of insects, but insects also produce disagreeable odours.
- Damage is generalized and not recognizable as being caused by this species
How to control
- Is found worldwide and across Canada
- Is usually found in association with damp, moldy grain
- Is most often found in dark and damp places, grain bins, sacks of feed, litter of chicken coops and birdhouses, stables, mills, elevators, warehouses, feed mills
- Is often found in association with the yellow mealworm (Tenebrio molitor)
- Adult females lay 400 to 500 eggs.
- Dark mealworms will readily feed on other insects.
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