Excerpts from Jim Conrad's
Naturalist Newsletter

from the August 23, 2009 Newsletter, issued from the Siskiyou Mountains west of Grants Pass, Oregon:
X-RATED BEETLE JUICE
The other day Chris in California wrote to tell me what was happening to him after he'd captured some large Blister Beetles for use as fishing bait. Blister Beetles excrete a colorless substance as a defense against being manhandled, and that's where his story began:

"I got the stuff all over my fingers, getting them out and putting them on the hook, not knowing what could happen because the stuff is invisible. Well, I am a nurse practitioner and when I saw my condition emerge I had concerns about painless genital swelling. The potential list of disease conditions was frightening. ... later, I got the idea that just maybe my condition had something to do with the bugs I caught."

Christ identified his bait-beetles as a kind of a blister beetle, read that blister beetles excrete a defensive substance known as Cantharidin, he Googled Cantharidin, and here's what he learned:

Male blister beetles transfer Cantharidin to females during mating. Cantharidin is toxic to many species so females cover their eggs with it as a defense against predators. And here's the part on Cantharidin's Wikipedia page that really got Chris's attention:

"If Cantharidin is ingested, it severely irritates the urinary tract as it is excreted, causing swelling of the genitalia. This can cause a harmful condition known as priapism in men, where an erection lasts more than about four hours."

Some men pay for Chris's symptoms, but I guess if you don't know why the symptoms are happening to you it can be pretty scary! There's more about Cantharidin at https://en.wikipedia.org/wiki/Cantharidin

Wikipedia's Blister Beetle Page is at https://en.wikipedia.org/wiki/Blister_beetle