Rusty Grain Beetle

species: cryptolestes ferrugineus
common names: rusty grain beetle
hosts: wheat, grain
notes:

Agriculture and Agri-Food Canada Insect Identification Sheet No. 78 March 1981 Rusty Grain Beetle Cryptolestes ferrugineus (Steph.) The rusty grain beetle is distributed widely throughout the world. It is a common pest in farm granaries and storage elevators in Canada, and on the prairies it is rated as the most troublesome of the pests that attack stored grain.

Injury:

Grain damage is caused by both the larvae and the adults of this species when they attack the kernels. The larvae and adults feed on the germ and endosperm. Heavy infestations of the insects also contribute to other damage by causing the grain to heat and spoil, and by spreading fungal spores in the stored grain.

Life History:

The adult is a shiny reddish brown beetle about 2 mm long. It moves rapidly in warm grain and lies when the air temperature is above 25 degrees. Each female is capable of laying 200 to 500 eggs, which are deposited loosely on or among the grain kernels and hatch in 3 to 5 days in a temperature of 30 degrees. The wormlike larvae are 3 mm long, white and have two brown projections at the tail end. In feeding they penetrate the germ-end where they pupate. Under conditions of 15% grain moisture content and  temperature of 32 degrees, the transition from egg to adult beetle takes about 4 weeks. The beetle will not develop in dry grain with a moisture content of less than 12% or when the relative humidity is less than 40%. Temperature limits for complete development are 20 to 40 degrees.

Control:

To prevent an infestation, thoroughly clean empty bins before loading new grain into them. To prevent re-infestation since the insect can fly on warm days, old residual grain should be destroyed by burning or by disposal in a sanitary fill. Drying and cooling grain shortly after harvesting is a valuable precaution. Infestations in bins can be controlled by treating the grain with a recommended fumigant or, in winter, by cooling the grain to - 7 degrees and holding it at this temperature for at least 6 weeks. Consult your provincial agricultural representative for full details on the control of this pest.