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Blister Beettles in Field Crops & Using Flea Beetles for Leafy Spurge Control

County Agent News
Dan Folske
July 15, 2019 

BLISTER BEETLES IN FIELD CROPS

Ash gray blister beetles, Epicauta fabricii, have been reported in canola, soybean and alfalfa fields in central, northwest and north central areas of ND. Adult blister Ash Grey Blister Beetlebeetles can be an occasional pest causing defoliation to the leaves and clipping flowers or pods. In canola, they are attracted to blooming canola fields for its nectar and pollen, but they also devour leaves, flowers and pods. Blister beetles are a major problem in alfalfa / hay fields or in bales, since they produce a toxic chemical (cantharidin), which is toxic to livestock, especially horses. Larvae of Epicauta species actively prey on grasshopper egg pods.

Blister beetles are mobile and gregarious, and often congregate in certain spots in a field (edges). These beetles are gray in color, about 1/8 inch wide and ½ to 5/8 inch long. In some instances, blister beetles only feed for a short period and then migrate to other fields. However, they can do a great deal of damage in a short time when their numbers are high.  Alfalfa and forage are preferred hosts of blister beetles and they often move into canola or other field crops after the alfalfa is cut. If treatment is necessary to avoid yield loss, producers can ‘spot treat’ with a foliar insecticide. Avoid spraying flowering crops for bee/pollinator safety.

Using Flea Beetles for Leafy Spurge Control

Leafy Spurge Flea Beetles are active and now is the time to collect and move them. You will not hurt established populations by moving them. Look for areas with last year’s dead stems of spurge but less current year growth.  Work these areas with a sweep net and move to new locations. If you are moving them to a location more than walking distance you can place them in a paper bag in a cooler with an ice pack for up to 24 hours.

Don’t place them in the middle of a heavy dense stand. Release them on the edges of dense stands or trees. If you have a very large dense stand you may want to knock down and area of at least 20 feet by 20 feet with a weed eater to open up the canopy. Ideal release sites are open, sunny and well drained.

Filed under: Burke news
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