Blister Beetles

Desert Blister Beetle - Lytta magister

While we were at the Desert Mountains Art Faire this past weekend, we were fortunate to observe a large number of Blister Beetles swarming over the encelia bushes outside the entrance to the National Monument Visitor Center.

The beetles were extremely active - eating, crawling, flying, and procreating. Many were multi-tasking, and all were enjoying their insect version of  Spring Break.


The beetles are large - nearly 1-1/2" long - with a bright red head and prothorax, and a black abdomen. They are ponderous flyers, and their wings create a deep humming noise in flight. With their interesting name and space alien looks, I definitely wanted to learn more about them.

Blister Beetles are so-named because they secrete a defensive blistering agent called cantharidin. This compound causes blisters and chemical burns on contact with skin. Cantharidin can be fatal if ingested, and the beetles can be especially problematic when they occur in alfalfa hay that is fed to horses, as accidental poisoning can result. Cantharidin collected from a European blister beetle species has historically been used in the preparation of "Spanish Fly".

Desert Blister Beetle - Lytta magister

There are about 7500 species of Blister Beetles world wide, and most of them have bright coloring to warn potential predators of their toxicity.

These particular beetles that we saw are the Desert Blister Beetle, or Master Blister Beetle. They occur in southwestern North America and  are often seen in swarms in the spring.





"If one could conclude as to the nature of the Creator from a study of his creation, it would appear God has a special fondness for stars and beetles."

~ J.B.S. Haldane (apocryphal), British geneticist and evolutionary biologist