Blister Beetle

Gardener's friend or foe? The answer depends on this insect's life stage.
Related To:
ISP-9612514_Blister-Beetle_s4x3

ISP-9612514_Blister-Beetle_s4x3

Named for the effect it has on human skin, the blister beetle is both a gardening pest as well as a friend, depending on its stage. As a larva, it feeds on grasshopper eggs but as an adult, it feeds on alfalfa and a variety of vegetable crops, depending on the species. More than 300 species of blister beetles are found in the U.S. — many (but not all) have long and narrow bodies; in nearly all, however, the head is larger than the body segment next to it. Color ranges from solid black or gray to striped or metallic.

Blister beetles contain a toxic substance, cantharadin, that can cause blisters to form on the skin. The toxin is especially problematic for livestock that eat feed contaminated by the beetles. Horses are especiallly susceptible; horses that eat sufficient quantities of the feed can become extremely ill and die. Blister beetles vary in the amount of cantharadin they contain. It's been estimated that 80 three-striped blister beetles or 1,100 black blister beetles would provide a lethal dose of cantharadin for a 550-lb. horse.

Applying an insecticide is usually not an effective control for the blister beetle. Hay growers typically use mechanical means for getting rid of the pest. If you find blister beetles in your veggie garden, pick them off by hand — and be sure to wear gloves!

Keep Reading

Next Up

Stag Beetle

Not considered a pest, this beetle lives on decaying wood in tree stumps and fallen logs.

Ground Beetle

This fast-running beetle is a friend to gardeners.

Gardening Q & A: Summer Snowflake Plant and More

Master gardener Paul James talks about pruning candles, cool plants, and no-hassle manure tea.

How to Garden in Just 15 Minutes a Day

No time to garden? Learn 10 easy tricks to multiply minutes in the garden.

In the Zone: Understand Climate and Hardiness

Knowing the local climate is the first step in understanding hardiness and hardiness zones.

When to Use Pesticides and Fungicides

Chemicals aren't always needed. Learn when -- and when not -- to use pesticides and fungicides in your garden.

9 Reasons Why You Should Never, Ever Garden Naked

Before you celebrate World Naked Gardening Day, consider the consequences. 

All About Sunflowers

Take a new look at sunflowers, including some exciting and unexpected varieties.

Discover the Joys of Pond Gardening

Maintaining a tranquil water garden is easier than you think.

Decipher Plant Descriptions

Confused on what those gardening catalog words mean? Learn how to decipher plant descriptions.

1,000+ Photos

Browse beautiful photos of our favorite outdoor spaces: decks, patios, porches and more.

Follow Us Everywhere

Join the party! Don't miss HGTV in your favorite social media feeds.