Blister beetles are sometimes found in mid-summer cuttings of alfalfa hay and can be toxic if consumed by livestock, especially horses. As few as 5 to 10 of these beetles can be fatal to horses when ingested because of the cantharidin in their hemolymph (insect blood). Management to minimize blister beetle problems in alfalfa:
· Cut alfalfa at 10% or less bloom
· Manage weeds in and around fields, especially pastures
· Consider cropping practices adjacent to alfalfa. Blister beetles can be abundant in soybeans but are usually absent in corn.
· Do not grow solanaceous crops near alfalfa – both black and stripped blister beetles can be abundant in tomatoes and potatoes
· Sample field margins before cutting – blister beetles usually come from field margins and do not tend to move too far beyond the edges of alfalfa fields
· Monitor pastures for grasshoppers. Several blister beetle species develop in grasshopper egg pods. A high grasshopper population can produce high blister beetle numbers the following year.
Read more about blister beetles in the June issue of KY Pest News
~ Ric Bessin, from KY Pest News. Management steps from Lee Townsend.