This Arizona beetle can cause a poison ivy-like rash if you swat it

By Tom Maxedon
Published: Monday, April 24, 2023 - 8:00am
Updated: Monday, April 24, 2023 - 8:18am

A blister beetle
John Alcock
A blister beetle can excrete yellow oozing blood to keep predators away. The insect's blood can also cause blisters on human skin.

Crane flies and mosquitoes have received a lot of news attention lately, but have you ever heard of blister beetles?

Arizona State University researcher Andrew Johnston said the insect is native to Arizona and can cause a poison ivy-like blister should one land on your skin and you swat it.

“A blister beetle, when they’re disturbed, can excrete blood out of their joints. Or, if one lands on you, you get frightened and you squish it, it would bleed on you and in that blood is a chemical that will cause our skin to blister,” he said.

The 2- to 3-inch beetles have a square head and brightly-colored bodies. The insects are usually seen crawling but they do fly. If one lands on you, Johnston recommended brushing off the bug very gently.  


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