Insect pests found in stored grain

In Canada there are approximately 55,000 species of insects, a small number of which are considered as pests. The Canadian Grain Commission recognizes over 50 species of insects (including grain mites) as pests of stored grain. Some are considered Primary pests because they infest and cause damage to whole sound grain, while some are considered Secondary pests because they require grain that is going out of condition or is damaged to allow these insects to infest and thrive. If left unattended, primary insect pests of grain will cause considerable damage. The discovery of Secondary pests is less significant and their presence indicates that storage conditions are less than optimal for maintaining grain quality and this in turn, is an indicator of other potential problems.

Primary insect pests are not tolerated in the Canadian grain handling system. The Canadian Grain Commission monitors railcar shipments, container and vessel loadings and grain elevators for the presence of live insects. When insect pests are discovered, the Canadian Grain Commission has jurisdiction to require treatment or disposal of infested grain.

Status

• Primary insect pests - an insect that can infest, establish in, feed upon and reproduce in whole sound grain.
• Secondary insect pests - an insect that can infest sound grain, but can only thrive on grain material that is damaged or going out of condition.

The Canadian Grain Commission identifies 20 species of insects as primary pests (19 beetle species and 1 species of moth). Over 33 species are considered to be secondary pests (21 beetle species, 11 moth species, booklice species and grain mites). The following eight insect species are the most frequently encountered in stored grain in Canada:

1. Rusty grain beetle (primary)
2. Red flour beetle (primary)
3. Confused flour beetle (primary)
4. Sawtoothed grain beetle (primary)
5. Granary weevil (primary)
6. Rice weevil (primary)
7. Yellow mealworm (secondary)
8. Lesser grain borer (primary)

The pests listed are grouped by pest status, as primary or secondary. They are organized alphabetically by insect order (Coleoptera: beetles, Lepidoptera: moths, Pscoptera: booklice), family and scientific name. The common name is listed first on the pest status lists and pest fact sheets.