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Blister Beetles in Canola and Forage (07/06/17)

Nuttall’s blister beetles, Lytta nuttalli, a large purplish green beetle have been reported in canola, soybean and alfalfa fields in southwest, south central and north central areas of North Dakota.

Blister Beetles in Canola and Forage

Nuttall’s blister beetles, Lytta nuttalli, a large purplish green beetle knodel.6have been reported in canola, soybean and alfalfa fields in southwest, south central and north central areas of North Dakota. It is not a known pest of soybeans. However, blister beetles can be a problem in alfalfa and forage, either in the field or in bales, as they are toxic to livestock, especially horses. For more information about blister beetles in hay and forage, see the NDSU Extension publication E1002 Blister Beetles. In canola, adult blister beetles are attracted to blooming canola fields, where they devour leaves, stems, flowers, and pods. Blister beetles are mobile and gregarious, and often congregate in certain spots in a field. In some instances, blister beetles only feed for a short period of time and then migrate to other fields. Alfalfa and forage is a preferred host of blister beetles and they often move into canola or other field crops when the alfalfa is cut.

The presence of large numbers of blister beetles in spots of a canola field has often concerned producers. However, adult feeding is generally not significant enough to warrant an insecticide treatment. The “High Plains Integrated Pest Management Guide” recommends treatment when there are 10 adult blister beetles per plant feeding on the flowers or pods. If treatment is necessary, producers can ‘spot treat’ with foliar insecticide registered in canola.

Please consult the 2017 North Dakota Field Crop Insect Management Guide for information about insecticides for control of blister beetles.

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