It sounds like something out of a horror movie.
A colorful beetle that may look harmless, but it secretes a toxin so strong, it can even kill a horse.
When it comes into contact with human skin, however, the effect of this toxin can lead to extremely painful blisters.
One emergency room doctor described it as a chemical burn.
Dr. Joanna Woods can describe that intense pain firsthand.
"I went through an entire tissue box of tissues crying my eyes out. It felt, not like an itch; it's like I put my arm on a skillet and couldn't take it off. It's just excruciatingly painful," Woods said.
Woods says she feels certain she encountered the blister beetle while watching a movie at a Valley movie theater.
"Midway through the movie I started saying, oh I'm starting to feel a little itchy, there must be mosquitoes in here," Woods said.
Then she thought it might be bed bugs.
She saw red welts on her arm as she left the movie theater, within hours those welts were turning into big, marble-sized blisters.
Welt went to the pharmacy to get medicine, the pharmacist on duty advised her to go to an Urgent Care, and the Urgent Care physician advised her to go to an emergency room.
Even in the emergency room, Woods said staff appeared to be stumped by the size of these huge blisters all over her arm.
"I had nurses in there saying I've been doing this for 35 years, I've never seen his, what is it?"
Woods was hospitalized for two days due to concerns over the swelling and treat of infection.
ABC15 Arizona reached out to Eric Godinez, the owner of Scorpion King Exterminating, who said he was familiar with the colorful blister beetle.
"There is a time of year that blister beetles migrate through the Valley, usually through farmlands that contain alfalfa and hay," Godinez said.
They are also found in backyards, where they munch on flowers and leaves.
Godinez said these beetles would only attack if provoked.
"If you brush them off or try to squash them, they secrete a toxin that is very lethal. It will stay released for about 2-3 months even after it's dead," Godinez said.
He advised leaving it alone if you happen to encounter one in your backyard.
Phoenix is home to the "Master Blister Beetle."
The bug has wings, and Godinez said it was a short flyer.
How it got into a movie theater, or on Woods' skin is still a mystery.
"I just wished it had never happened. It was excruciatingly painful," Woods said.
She is now talking to management at the movie theater to get to the bottom of it.
Woods does admit she does have severe reactions to most bug bites, so just like anything, different people can have different reactions if exposed to the toxin from his beetle, but doctors said it lives up to its name, the blister beetle.