Blister Beetles in Vegetable Gardens
While we most commonly think of blister beetles being a pest in hay crops, especially for horses, these insects can be a major pest of vegetable gardens. There are several different species of blister beetles in Kansas and they range in size from ½ to ¾ of an inch long and in color from black to gray to brown striped. No matter what size or color, blister beetles can be identified by their elongated, narrow, cylindrical bodies with the middle body being narrower than the head of the wing covers. These beetles can quickly strip vegetables, especially tomatoes, within a couple days if there are enough of them. These insects tend to congregate in groups on flowers and leaves of plants in the families Amaranthaceae, Asteraceae, Fabaceae and Solanaceae.
Blister beetles get their common name because the beetles contain a substance called cantharidin which can cause large, erect, watery blisters. If you have a few blister beetles you can removed them and drop them in a bucket of soapy water but be sure to wear gloves when handling them to prevent injury. If there are large numbers of these insects chemical control maybe your only option. Use products with the active ingredient’s permethrin, pyrethroids, cyfluthrin or bifenthrin. Unfortunately, other than removing the beetles and squishing them or putting them in soapy water there aren’t any cultural control methods that are effective for them.
