OHHHH, I'm VERY familiar with these. I am TERRIFIED of them, because they FLY!
My first encounter was in Palm Springs, an outbreak in the mid 80's. I was jogging (early evening?)and they were flying everywhere. They're huge, with HARD black shells that would dent a car-LOL. And I couldn't get away from them! They were in a guy's shower, and someone's car!
Next, I had them in Tucson. I have a greenthumb, and misters, and...you can imagine! They knew I was terrified, and when I was outside, they would land on my screendoor, knowing I wouldn't go in till it was gone! One got in my 2nd bdrm, no one would help, and I didn't go in there for 6 weeks! Try to kill them, spray a can of raid--3 days later STILL moving their creepy crawler things!
Now in Yuma, AZ, only a few times, but that means they're looking for me. Oh, one time in Elephant Butte, NM, my cat tried to bring one in!

And until now, I didn't know those grubs I kept finding in Tucson were from them--they were disgusting too!
There's an old "Outer Limits" episode with ANTS that remind me of them (1963 graphics were hilarious, but not to me!), and seriously, I'd be more afraid of someone pointing one of those at me than a loaded gun!
Yes, monsoons, moisture, heat, is their environment. The grubs can live for 3-4 years, says the Desert Museum in Tucson.

I had an outbreak of these when I first moved here (near joshua tree nat'l park)in 07. I kept finding almond shaped holes around my oleander, pine, palm and pyrocanthus trees. After ID on this website, and a diagnosis of few known remedies for them, to save my oleander trees, I began to flood the holes with hose. Best success around sunset--small trickle so you don't cave the hole in--they'll just dig their way out somewhere else. I have about a 25% success rate w/ this method-logical if one insect makes multiple holes. They will climb out of their holes and you can nail it quickly.

After a year of peace, they are back again. After having the house and yard recently exterminated (pyrethins [sp?]) a few died and showed up near the house. Approx. 3", not including monster antlers. Something happened, and a month later, they have multiplied exponentially, with 10 holes showing up near my pyrocanthus hedges, and major die off within 10 days of my grapefruit and lemon tree. The latter is nearly denuded completely of leaves, w/ entire branches suddenly dead. According to an email from one of the authors of another website (bugman?) they like non-native trees, and ornamentals--not just palo verdes for whom they were originally named. This is evident in my yard--I have only one PV--outside my fenceline.
After reading a bit, I'm wondering if the adults lay eggs that take more than a year to hatch--hence the peace last year, and allowing my trees/shrubs to recover.
You can kill these monsters--just takes patience to drown them out.
For ease, I will try the grub stuff mentioned in 2007 post, and more of the pyrethin pesticide as it has least effect on the lizards and birds that flock to my house.
So much for lemons and grapefruit this year.

In 2005 I found two of these Monsters. I found one a few days ago in the pool, and just yesterday in ti the pool. These things freak me out.
How can I find out where they are coming from?
Help

I found one this morning, a male hu
sweet mines 2 and a half inches long though i saw the females these are big bugs:3

Yes, thank you for posting here to Bugguide! This is a male palo verde root borer, Derobrachus geminatus, in the longhorned beetle family Cerambycidae.