burning blister beetles

(Epicauta spp.)

Overview

Epicauta is a very large genus of small to medium-sized beetles. There are about 360 described Epicauta species worldwide, 264 species in the New World, 173 species in North and Central America, and at least 10 species in Minnesota.

Epicauta occurs worldwide on every continent except Australia and Antarctica. Some are significant agricultural pests and can even cause a crop failure if they appear in large enough numbers. Like all blister beetles, they contain the toxin cantharidin in their bodies. Some, including Epicauta occidentalis, contain low levels of cantharidin. Others, especially black blister beetle, contain very high levels of the toxin. When baled into hay in large numbers it can sicken or even kill horses.

 
burning blister beetle (Epicauta sp.)
Photo by Bill Reynolds
 

The larvae of all species are predators of grasshopper eggs. Most adults feed on the leaves and flowers of plants, especially legumes. Some species, including black blister beetle and Epicauta occidentalis, feed exclusively on pollen and nectar.

Description

Adults are to 1116 (4 to 18 mm) in length. The body is elongate, slender, and soft.

The head is broad and somewhat rectangular when viewed from above. It is distinctly separated from the first segment of the thorax (prothorax) by a short neck. The antennae have 11 segments and on most species they are thread-like. The mouthparts are directed downwards.

The upper plate covering the prothorax (pronotum) is narrower than the head and narrower than the base of the wing covers (elytra). It is rounded on the sides.

The elytra are soft and leathery. They are loosely rolled over the body on the sides. They cover most of the body but leave the tip of the abdomen exposed.

The legs are long and slender. On the front legs, there is a patch of silky hairs on the underside of the third segment (femur). On the front and middle legs, the last part of each leg (tarsus), corresponding to the foot, has 5 segments. On the hind legs the tarsus has just 4 segments.

Distribution

Distribution Map

 

Sources

24, 27, 29, 30, 82, 83.

8/16/2025    
     

Occurrence

 

Taxonomy

Order

Coleoptera (beetles)

Suborder

Polyphaga (water, rove, scarab, long-horned, leaf, and snout beetles)

Infraorder

Cucujiformia

Superfamily

Tenebrionoidea (darkling beetles and allies)

Family

Meloidae (blister beetles)

Subfamily

Meloinae

Tribe

Epicautini

   

Subordinate Taxa

Subgenus Epicauta

Subgenus Macrobasis

   

Synonyms

Anomalonychus

Anomalonyx

Apteropasta

Apterospasta

Causima

Causima

Epiacuta

Gnathospasta

Henous

Isopentra

Macrobasis

Maculicauta

Nomaspis

Pleuropompha

   

Common Names

burning blister beetle

 

 

 

 

 

 

 

 

 

Glossary

Elytra

The hardened or leathery forewings of beetles used to protect the fragile hindwings, which are used for flying. Singular: elytron.

 

Femur

On insects and arachnids, the third, largest, most robust segment of the leg, coming immediately before the tibia. On humans, the thigh bone.

 

Pronotum

The exoskeletal plate on the upper side of the first segment of the thorax of an insect.

 

Prothorax

The first (forward) segment of the thorax on an insect, bearing the first pair of legs but not wings.

 

Tarsus

On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.

 

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Bill Reynolds

burning blister beetle (Epicauta sp.)   burning blister beetle (Epicauta sp.)
     
burning blister beetle (Epicauta sp.)   burning blister beetle (Epicauta sp.)
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Bill Reynolds
7/23/2017

Location: Pennington Co MN

burning blister beetle (Epicauta sp.)
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Created: 7/28/2017

Last Updated:

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