Friday, 15 May 2020

Spring threshing surprise - Seeking beetle data please!

Large numbers of adult Amara ground beetles are being reported this spring (Fig. 1) in canola fields left unharvested last fall. These are non-pest beetles.  Adults feed on seeds, particularly those of cruciferous plants.  Larvae eat pest insects (e.g., grasshopper eggs).

Figure 1. An aggregation of Amara littoralis near Pickardville, AB. This was one of several outbreaks of
carabids observed in central Alberta in the autumn of 2010.  Photo B. Berry.

View another image of this beetle species at Bug Guide.  More images and life history information is available online at the Royal Alberta Museum or read this published Scientific Note by Floate and Spence (2015) describing previous reports of this species.

High numbers of these beetles may be due to an abundance of canola seed left on the ground last fall, which would have provided an ample food supply for adults going in the winter.  These overwintered adults have now emerged and are active.  They will lay their eggs in the soil during the next few weeks with their adult progeny emerging in late summer, which may generate more reports of their high abundance.

Dr. Kevin Floate (AAFC-Lethbridge) is interested in studying this phenomenon. If you observe an ‘outbreak’ of ground beetles, Dr. Floate is looking for the following information:
1. General location
2. 30 to 50 adult beetles collected from the ‘outbreak’ for identification (these can be stored in a small jar of rubbing alcohol)
3. Cropping history of the field where the ‘outbreak’ was observed, going back at least 2 years
4. The scope of the ‘outbreak’ (i.e. the number of acres affected), and
5. An estimate of beetle density (e.g., best guess of number of beetles per m2 or high resolution pictures of the outbreak)

Please contact Dr. Floate directly ( if you have observed a ground beetle ‘outbreak’ and are able to share information.

Thank you!