Blister beetle identification (Epicauta spp.)


Insect identifier · Ants, bees, and wasps

How to identify a Blister beetle

Epicauta spp.
· Also called spanish fly, epicauta, oil beetle

Blister beetle identification photo

People searching “what does a blister beetle look like” or “blister beetle bite” want a field ID, not a scare. Blister beetle (Epicauta spp.) is a ants bees wasps in this guide. Also called spanish fly, epicauta, oil beetle.

A burn after smashing a gray beetle on your arm is cantharidin, not a sting.

What does a blister beetle look like?

Blister beetle is About 10–20 mm. Colors people notice: black, gray, yellow. Field marks: Soft body, narrow neck; Often on alfalfa, potatoes, or flowers; Blister if crushed, not if it flies past.

Blister beetle is About 10–20 mm. Colors people notice: black, gray, yellow. Field marks: Soft body, narrow neck; Often on alfalfa, potatoes, or flowers; Blister if crushed, not if it flies past. If the marks fail, open the look-alike pages before forcing this name.

Identification marks

  • Soft body, narrow neck
  • Often on alfalfa, potatoes, or flowers
  • Blister if crushed, not if it flies past

Size: About 10–20 mm
Colors: black, gray, yellow
Where: outdoor

What a typical blister beetle bite looks like

Typical blister beetle bite or sting
A typical pattern. Reactions vary. This is a guide photo, not a diagnosis.

A blister or burn hours after crushing the beetle on skin. Not a puncture sting. Do not crush it on skin Wash with soap

A blister or burn hours after crushing the beetle on skin. Not a puncture sting. Fever, spreading redness, or trouble breathing needs a clinician.

If you were bitten

  1. Do not crush it on skin
  2. Wash with soap
  3. Seek care for a large blister or eye exposure

Blister beetle vs Velvet ant

Crush injury with a blister = blister beetle. Fuzzy red-black runner = velvet ant.

Range and season

Blister beetle is active summer. Typical places: garden, field. Soft beetles that release cantharidin. Crushing one on skin can blister. Not a stinger.

Gardens and alfalfa fields in summer.

Soft beetles that release cantharidin. Crushing one on skin can blister. Not a stinger.

Summer

Common questions

Do blister beetles sting?

No. The chemical in their blood blisters skin if you crush them.

Blister beetle vs velvet ant?

Velvet ant is fuzzy and stings. Blister beetle is a shiny soft beetle that blisters if crushed.

Related identification pages