Earlier this year I moved from a 20-year old suburban 2-storey home in Gilbert to a bungalow of similar age in Apache Junction.

The Gilbert house always had typical issues with Bark Scorpions. Despite having the house treated outside monthly by a pest control company, I'd see live scorpions out in the yard regularly and sometimes inside the house (particularly during monsoon). As the neighborhood aged, the number of scorpions declined but they remained a problem until we left.

The new AJ house is on the edge of the desert and we see a lot of wildlife outside (everything from coyotes to rabbits to roadrunners). We also see a lot of evidence of insect life in and outside the house (spider webs filled with bugs of all kinds). What puzzles me, though, is that I've seen just two live scorpion inside the house (plus two more in the garage) but I have seen about 3x that number of DEAD scorpions. We have cats so I initially assumed they had killed them, but I've also found a couple of dead ones in rooms the cats don't get into.

Don't get me wrong - I'm not unhappy the little bastards are dying but it is a bit of a mystery as they've always seemed like tough critters... what could be killing them? Whatever it is is not eating them as they appear undamaged. A few thoughts occurred to me:

1) Could the previous owners have applied some aggressive or unusually effective pesticide inside the house (better than the pest control companies use)? If so, do I need to worry about our cats getting sick?
2) The previous owners were apparently heavy smokers. I know nicotine has insecticidal qualities... might scorpions be unusually susceptible?
3) Maybe we have something else living in the house that kills scorpions (Black Widows?)
4) Other?

Any thoughts from the scorpionology brain trust here?

Diatomaceous earth or some sort of wetable powder?

Maybe, but I'm not seeing any powder residue around the house... maybe inside the walls?

Possible the prior owners sprayed with cy-kick and or had delta dust as well. I do not believe cy-kick is harmful to cats once dried, and it has a residual of up to 3 months, though honestly I start checking on effectiveness at about 6 weeks. With this much rain it might be even less.

Apparently some pest companies will use cy-kick as well, but will drop the concentration a bit.

The delta dust is something you can spray into cracks and can last quite long even when wet. If I had my guess I'd probably go with cy-kick, the dust is lesser known and it quite a mess.

Thanks. I've been here 6 months without applying any form of pest treatment and it has rained a lot here during the monsoon, which is why I assume if they used anything it would have to be inside the house or in the walls. No deposits of any solid powder/dust material are evident. The cats seem healthy.

Six months is way outside the potential residual of cy-kick, and you wouldn't be spraying in March as scorpions wouldn't be that active yet. Whatever it is let me know when you figure it out, I need to get my hands on it.

Got a lot of these looking flowers around your home?

https://en.wikipedia.org/wiki/Pyrethrum

The past two years I have been blacklighting and mapp gas burning scorpions outside.  My high was 12 in one night.  I only killed around 6 in the house in a 3 year period and have never found a dead one inside.   So far this year, I have only seen one or two and none after all of these rains.

I use Demon WP and also put down a lot of DE.  I honestly don't know if it is the chems or the climate that has the numbers down.

My first 10+ years in AZ, I didn't see a single one.

Sadly not - just wild desert flora.

Some brands of cat litter contain diatomaceous earth but unless you're entire house is a litterbox there's likely not enough of it floating around to kill scorpions in random rooms.

Borax kills them in the same manner but, again, not likely to be a ton of that just waiting for them to crawl through.

It's possible the previous owners identified the points of entry and just crammed them full of diatomaceous earth and the scorpions get coated in it as they enter then eventually die.

Two questions:

1) Ranch house or multi-level?

2) The cats don't get in those rooms or you don't think the cats get in those rooms? A lot of people think their cats don't get up on their counters either until they set up a camera while they're asleep.

Here is a piece of information for you... the sewers in AZ are loaded with cockroaches which provides an all you can eat buffet for scorpions that are also in the sewers... when people have a bathroom, sink or shower etc in their homes that they seldom use .. the water in the P traps evaporates and allows these roaches and scorpions entrance to your home.
They need a source of water to survive in your home and if they can’t find it they die quickly

You are most likely to only see dead scorpions, no matter what kills them, because when it is bright out,
they tend to hide in cracks so thin you would not think anything is in there.

Our house is surrounded by desert and I can kill up to 24 scorpions in one night,
but only find one live in the house every two or three years.
And find a dead one almost every month.

I'm just glad you made it out of Gilbert!

Three dead ones found in my house last week, two in the same day.  All the little ones (bark?).  One stung my foot in the garage a few years ago.  Found one in my daughter's bedding during the faux lockdown last year.  That one was alive.

I have a UV light in my kitchen to capture gnats, because I have a lot of house plants.  I find 99999 dead bugs under my windows, outside the home, as they are attracted to the leaking UV light all night long.  Most likely the scorps are into all the bugs the UV light is attracting through my windows and blinds.