Blister Beetle

The family Meloidae, blister beetles, contains about 2500 species, divided among 80 genera and three subfamilies

Description: Blister beetles vary by species in shape, size (3/8 to 1 inch long) and color (solid gray to black or with paler wing margins, metallic, yellowish striped or spotted). Most are long, cylindrical narrow-bodied beetles that have heads that are wider than the first thoracic segment (pronotum). The wing (elytra) covers are usually soft and pliable.

Although over 100 species occur in Texas, common blister beetles include:, the black blister beetle; Epicauta pennsylvanica (De Geer), E. occidentalis (east and central Texas) and E. temexa (south Texas) are mostly orangish-yellow with three black stripes on each of the wing covers (elytra). A west Texas species, Cysteodemus armatus LeConte, has wing covers that are broadly oval and convex, colored black with bluish or purplish highlights. Blister beetles, Epicauta sp. (Coleoptera: Meloidae), mating on Texas mountain laurel. Photo by Drees

Life Cycle: Complete metamorphosis; hypermetamorphosis. Winter is spent in later larval stages and pupation occurs in the spring. The pupal stage lasts about 2 weeks and adults appear in early summer. Female beetles lay clusters of eggs in the soil. The first stage (instar) larva hatching from the egg (triungulin) is a tiny, active, long-legged larva that seeks the appropriate host. Blister Beetle Life Cycle A = adult, E = egg, T = first instar or triungulin, FG = first grub phase, C = coarctate phase in instar six or seven, SG = second grub phase, P = pupa

Habitat and Food Source(s): Mouthparts are for chewing. Blister beetle species feed on flowers and foliage of a wide variety of crops including alfalfa, ornamental plants, potatoes, garden vegetables and other plants. Black blister beetle, Epicauta pennsylvanica (DeGeer) (Coleoptera: Meloidae), on goldenrod flowers. Photo by Drees

Medical and Veterinary Importance Blister beetles receive their common name from the ability of their hemolymph to produce blistering on contact with human skin. Hemolymph is often exuded copiously by reflexive bleeding when an adult beetle is pressed or rubbed. Blisters commonly occur on the neck and arms, as the result of exposure to adult beetles attracted to outdoor lights at night.

Pest Status: Adults usually occur in loose groups or swarms that feed on leaves of certain plants, especially legumes. Their bodies contain a toxin (cantharadin) that can cause blisters to form on the skin. Animals, particularly horses, ingesting beetle contaminated feed become extremely ill and may die. Handling blister beetles can cause blisters on the skin as a reaction to cantharadin

Cases of fatal poisonings of valuable horses in Florida, Oklahoma, Tennessee, and Texas by ingestion of blister beetles trapped in baled alfalfa hay

Cantharidin Highly toxic to horses, humans, sheep, goats, canine, feline, cattle. Clinical signs usually appear quick- 6-8 hours. No specific antidote…. Only supportive care. Only takes 6-8 g of dried beetles to be toxic.

Clinical signs: (include but not limited to) Colic symptoms-abdominal pain Animal Restless-urinary tract irritation Sweating Mucosal hemorrhage Cardiovascular problems GI problems-diarrhea Neurological problems

Prevention Be able to identify beetles. Always know the source of where Alfalfa is being grown and ask about the prevention of beetles. Blister beetles usually appear in the warm months of June-Sept. Harvest hay before these months. Harvest hay before the blooming of flowers. Inspect hay before feeding.