Wireworms are the larvae of click beetles (Coleoptera: Elateridae). They are serious pests of many field crops across Canada, particularly cereals, pulses, root crops. Wireworms live for multiple years in the soil, eating crops from below – their underground habitat can make them difficult to detect and diagnose. Damage in cereals and pulse crops will appear as early season crop thinning or yellowing, weakened plants. Root crops may look fine aboveground but at harvest, produce will have feeding holes or disfigurations, decreasing market value.
There are several pest wireworm species in the Prairies and they are different than in other regions of Canada. A 2004-2019 survey of Prairie crop fields published by Wim van Herk and colleagues collected 5,704 specimens. This survey revealed that 97% of specimens belonged to 4 native species: 58% were Hypnoidus bicolor (no common name), 22% were Prairie grain wireworm (Selatosomus aeripennis destructor), 15% were sugarbeet wireworm (Limonius californicus), and 2% were flat wireworm (Aeolus mellillus). Importantly, the invasive wireworm species dominating coastal BC and the Atlantic provinces (Agriotes obscurus, Agriotes lineatus, Agriotes sputator) were NOT found in the survey. Over the next several weeks our Insect of the Week articles will highlight the main pest wireworm species on the Prairies.
Monitoring for wireworms can be done in different ways. Before seeding, bait traps can be placed in the soil. After crop emergence, hand digging in thinned areas of crop may reveal wireworms. Finally, monitoring for adult click beetles may be able to indicate if wireworm populations are high – this method is still in development. Unfortunately, there are no economic thresholds developed for wireworms, farmers need to judge yield loss from thin or bare patches caused by wireworms.
AAFC has recently released a new field guide on Prairie pest wireworms. It has information on biology, monitoring and management and research on wireworms on the Prairies.
Free digital copies in both official languages can be downloaded at these links.
Free hard copies are also available while supplies last. Email firstname.lastname@example.org to request your copy.
van Herk WG, Vernon RS, Labun TJ, Sevcik MH, Schwinghamer TD (2021) Distribution of pest wireworm (Coleoptera: Elateridae) species in Alberta, Saskatchewan, and Manitoba (Canada). Environmental Entomology 50:663-672. doi: 10.1093/ee/nvab006