Bug Identifier

Beetles

Blister Beetle

Epicauta spp.

010203040
Body length in millimeters. Shaded bar shows the typical adult range.
Scientific nameEpicauta spp.
GroupBeetles
Size8–25 mm (up to about 0.98 in)
Colors Black, Gray and Orange
Legs6 legs
WingsYes
Where foundGarden or plants
Most activeSummer
BitesNo
StingsNo
Risk levelCan bite or sting

How to identify it

The blister beetle is a medium-sized member of the beetles group. Hard wing covers that meet in a straight line down the back. Check for these three features:

  1. Long, soft, cylindrical body with flexible wing covers
  2. Head wider than the narrow neck behind it
  3. Often black, gray or striped orange and black

About this bug

A long, soft-bodied beetle with a narrow neck that feeds on flowers and vegetable foliage. Its body contains cantharidin, a chemical that raises blisters on skin.

You'll usually find blister beetles in gardens and on plants. They are most active in summer.

Is it dangerous?

Handling or crushing blister beetles can cause painful skin blisters, and hay contaminated with them can poison horses.

Our rating: Can bite or sting, meaning it can bite or sting, usually with mild, local effects.

When you'll see blister beetles

Blister Beetles are most active in summer. Summer heat speeds up development, so populations can grow quickly.

Typical places to check: garden or plants.

About beetles

The blister beetle is one of the beetles. Beetles go through complete metamorphosis: egg, larva (grub), pupa and adult. The larval stage often does the most feeding and damage, and it can last from a few weeks to several years depending on the species. Adults protect their flight wings under hard wing covers called elytra, which is why most beetles look armored and meet in a neat line down the back.

Look closely at larvae as well as adults. Grubs in soil, fuzzy larvae in closets and small worms in flour are all beetle larvae, and finding them tells you where the problem is centered.

What to do about it

  1. Knock beetles into soapy water with a gloved hand instead of crushing them
  2. Keep weeds, especially pigweed, cut back around the garden
  3. Cover susceptible crops with row covers during midsummer

Read the full guide: how to get rid of blister beetles.

Bugs that look similar

FireflyPhotinus pyralis10–14 mmHarmless

Size: Blister Beetles are larger, reaching 25 mm, while fireflies top out around 14 mm.

Frequently asked questions

What does a blister beetle look like?

Long, soft, cylindrical body with flexible wing covers. Adults measure 8–25 mm (up to about 0.98 in).

Does the blister beetle bite or sting?

It does not bite. It does not sting. Handling or crushing blister beetles can cause painful skin blisters, and hay contaminated with them can poison horses.

Where do blister beetles live?

Blister Beetles live in gardens and on plants.

When are blister beetles most active?

Mostly in summer.