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Canola Flea Beetles Emerging

Posted: May 08 2020


Warmer, spring temperatures have caused flea beetles in canola to start emerging from overwintering sites. Flea beetles are being captured in pheromone traps by Lesley Lubenow at Langdon REC and T.J. Prochaska at NCREC in Minot. Overall, low population densities are present and the cooler weather forecast will slow the emergence.

The striped flea beetle, Phyllotreta striolata (Fabricius), is small, 1/32 to ? in. in length, with two yellow strips on their black wing covers (Figure 1). They emerge earlier than the more common crucifer flea beetle, Phyllotreta cruciferae Goeze. Crucifer flea beetles are a black beetle with an iridescent blue sheen on the wing covers. Flea beetles have enlarged hind femora (thighs) on their hind legs, which they use to jump quickly when disturbed. Their name, flea beetle, arose from this behavior.

Phyllotreta flea beetles have a single generation in the northern Great Plains. They overwinter as adults in the leaf litter of shelterbelts or grassy areas and rarely overwinter in canola stubble. Beetles emerge when temperatures warm up to 57 to 59 F in early spring. Flea beetles feed on volunteer canola and weeds, such as wild mustard before moving to spring planted canola fields. Depending on the temperature, it may take up to three weeks for adults to leave their overwintering sites.

Warm, dry, and calm weather promotes flea beetle flight and feeding activity throughout the field, while simultaneously slowing canola growth. When weather conditions are cool, wet, and windy, flea beetles may creep slowly into the field and concentrate feeding on the field edges.

 
For more information, see the NDSU Extension publication E1234 (revised)
Integrated Pest Management of Flea Beetles in Canola (https://www.ag.ndsu.edu/publications/crops/integrated-pest-management-of-flea-beetles-in-canola).
 
Janet J. Knodel
Extension Entomologist
 

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