Avoid the black blister beetle

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This black blister beetle pair feed on wildflower blossoms in Aguanga. Diane Sieker photo

“Don’t touch it!” residents said.

The reputation of the blister beetle preceded its colorful appearance. The species Lytta vulnerata is found in the Anza Valley and is not safe to touch.

These critters pack a nasty defense and are hazardous to touch and poisonous to eat. Lytta vulnerata are a member of a family of beetles that uses toxic chemicals as a defense against predators or passersby. They carry potent cantharidin toxins that can interfere with a vertebrate’s nervous system.

The cantharidin is secreted from the legs and antennae when the beetle is handled or eaten, causing nasty blisters on the skin or mouth.

According to www.Insectidentification.com, the compound cantharidin has been used for wart removal for humans.

The bright reddish or orange head is a serious signal to go away and leave this insect alone. Biologists refer to this warning coloration as aposematism, from the Latin terms “apo,” meaning away, and “sema,” or sign.

Lytta vulnerata ranges in size from a half inch to almost an inch in length. They are active during the daylight hours, and can be commonly seen grazing peacefully on native wildflowers and plants.

If residents find any of these beetles, heed the warning and don’t touch it. Observe or take photos, but leave them alone.

Diane Sieker can be reached by email at dsieker@reedermedia.com.