The striped blister beetle is usually recognized as a potential toxic contaminant in alfalfa in mid-July, but potatoes and tomatoes are also high on its food list. In fact, one of its former common names is “old-fashioned potato bug.” This insect returned to this role late last week when a swarm of them defoliated potatoes and then turned to tomatoes in a Graves County garden.
Blister beetles are gregarious insects that accumulate on food plants where they feed and mate. Striped blister beetles hide beneath plants during hot periods of the day, becoming active when temperatures are more tolerable to them. Feeding beetles will immediately fall to the ground and run when disturbed, as shown in the following video by Trent Murdock, Graves County Extension agent:
Blister beetles begin feeding on edges of leaves, ultimately leaving only stems (Figure 2). Striped blister beetles live for about 40 days; however, adults do not emerge in a synchronized flush, so these insects can be found over most of summer. Large numbers of blister beetles are most likely near pastures or cultivated fields where the insects develop on grasshopper egg pods, which are laid in the soil.
Insecticides labeled to control beetles on crops that blister beetles are attacking should provide effective control.
By Lee Townsend, UK