Cereal leaf beetle (Oulema melanopus) - By this point in the season, pupae and newly emerged adults will be present in fields.
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 - 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 1). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They will emerge in the spring once temperature reaches 10-15 ºC.
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| Figure 1. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski). |
Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide".