blister beetle

US /ˈblɪstər biːtl/
UK /ˈblɪstər biːtl/
"blister beetle" picture
1.

a beetle of a family (Meloidae) that produces a substance (cantharidin) that irritates the skin and causes blisters, formerly used in medicine as a counterirritant and aphrodisiac.

:
The farmer warned us about the blister beetle in the fields.
Contact with a blister beetle can cause skin irritation.