By Wendy Langhans
The e-mail header asked, “Do you know what this is?” Whenever I receive an e-mail like this, I never know what I’m going to find. It could be simple, an easy-to-answer question or it could be a bit more challenging, like this one turned out to be. But there is an upside to a challenging question - I learn something new (and I can share what I learned with you).
The e-mail had an attachment - a picture of a black and red beetle.
Master Blister Beetle, (Lytta magister) Photo courtesy J. McDaniel
I went to my collection of books, grabbed “Introduction to California Beetles”, and began to browse. Sure enough, I found a matching photo. It was a Master Blister Beetle, (Lytta magister ).
But as any trained interpretive naturalist can tell you, naming something is just the beginning. As a naturalist  , you need to know enough about the “what” to be able, as an interpreter , to talk about the “so what”. It’s like being a jazz musician - taking the notes (the name), identifying the melody (the what) and improvising (the so what).
So what did I find out about Master Blister Beetles? To keep it short, I’m only going to focus on one “melody”: when disturbed, Blister Beetles exude a milky liquid containing cantharidin, a poisonous  chemical that can “cause the skin to blister”.
Now what can I do with this information? How can I take the “what” and turn it into a “so what”? This is where I get to be creative. Off the top of my head, I can think of three things:
1) Wart-B-Gone. Cantharidin has been used in medicine as long ago as the ancient Greeks and Romans. For example, did you know that cantharidin has been used to treat people for warts ? According to WebMD, “cantharidin causes the skin  under the wart to blister, lifting the wart off the skin. When the blister dries, the wart comes off with the blistered skin.” (Disclaimer - I am not an MD and am not suggesting this as a treatment.)
2) Blister Beetles “say it with Cantharidin”. Canthradin is used by some Blister Beetles as a “nupial gift”. Female Blister Beetles cannot produce canthradin, so the male provides a “gift” of canthradin during mating. When the female lays her eggs, she also lays down canthradin as a form of chemical protection again predators.
Master Blister Beetles transferring cantharidin. Photo courtesy W. Campbell
3) Eat at your own risk. Humans have been eating insects for tens of thousands of years - sometimes by accident and sometimes on purpose. But Blister Beetles should be avoided. Not only is canthradin poisonous  to humans, but it has been know to poison livestock, including horses  and cattle .
Thanks, Jeremiah, for your e-mail. It gave me a chance to learn something new.
Upcoming Outdoor Events:
Saturday, May 15, 8-10 AM. Early morning bird hike at Towsley Canyon. It’s an easy 1 mile walk and beginning birders are welcome. For map, click here .
Saturday, May 22, 9-11 AM. Native American Plant Use. Towsley Canyon. Our native California plants provide a bounty for native peoples. For map, click here .
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