I got to try out my "new" ankle on a short hike yesterday. We hiked about half way up Scottsdale's Pinnacle Peak, a 600 foot granite rock pile that was, like the boulders at Joshua Tree, formed by underground molten lava that was eventually exposed by erosion.
When we got part way up, we were suddenly surrounded by hoards of large black and orange insects, strangely flying with their abdomens held down. Most of them favored nearby bright yellow flowers, but some would land on us or "dive bomb" our heads. Talking was risky -- one would have flown into my mouth had it been open!
They turned out to be Blister Beetles, in the family Meloidae. Blister Beetles are so named because they secrete a poisonous substance called cantharidin. Cantharidin will blister human skin at contact, is medically used to treat warts, and is also known as "Spanish Fly." A few Blister Beetles unknowingly eaten by a horse can kill it.
The desert now has several plants in bloom. Ocotillo, cholla, and various cacti and flowering plants all have blossoms. Here is one of the cactus blooms from the hike: