If you're out hiking in the Southwest United States or in northern Sonora, Mexico, beware of the Lytta magister, also called the "master blister beetle." These bright black and red-orange bugs can grow up to several inches long and often hang out—in groups of up to several dozen—in flowering desert plants like the brittlebush shrub. What makes this bug something you should avoid? Arizona State University's Ask a Biologist explains:
Few of us are tempted to pick up great big, black and orange beetles and this makes sense when you find master blister beetles. The "blister" in the name refers to the beetle's ability to pop a blood vessel in the joint of a leg, which causes the insect's yellowish blood to ooze out. The beetles do this only when they are upset. For example, when held firmly by a person. The blood is not only bad smelling, it's downright dangerous, capable of causing skin to blister painfully. If a bird or mouse were to try to eat a master blister beetle, the hungry animal would get a mouthful of the disgusting blood, which might cause it to think twice about finishing the beetle off.
Bug Guide provides more information about the bugs, including photos are details about where they're found (California, Arizona, Utah, and Nevada in the United States, and northwest Sonora in Mexico).
The video I'm including shows a closeup of blister beetles mating while foraging for greens (what good multitaskers they are!). It was filmed in the Anza-Borrego Desert, California, and uploaded to the YouTube channel "Road."