The Tucson Monsoon Pest Checklist: Before, During and After the Storms

What the monsoon wakes up around a Tucson house

The Tucson monsoon wakes up four pests at once: desert subterranean termites, mosquitoes, bark scorpions and sewer roaches, with kissing bugs flying in just ahead of the first storms. The National Weather Service counts the season from June 15 to September 30, though the real rain often holds off until July.

Termites are the expensive one. University of Arizona Cooperative Extension bulletin AZ1369 says desert subterranean termite swarmers fly at dusk after a rain from July to September, and the extension's homeowner guide AZ1356 calls the end of the monsoon the stretch when termites are most active. The swarm is just the part you see.

Mosquitoes are the loud one. UA Extension's mosquito bulletin AZ1221 says Aedes aegypti glues its eggs inside pots, tires and buckets just above the waterline, where they can sit dry for up to a year and hatch when rain refills the container. Its usual flight range is 5 to 100 meters, so the mosquito on your ankle at dinner most likely grew up in your yard or the one next door.

Scorpions and roaches round it out. The UA community IPM team says bark scorpions are active when nights stay above 70 degrees, and Tucson's July and August lows average in the mid-70s by National Weather Service normals. The University of Florida IFAS profile of the American cockroach, our sewer roach, notes that infestations can follow heavy rain. Kissing bugs come first: a 2022 study by Schmidt, Klotz and Miller in the Tucson foothills found them flying to lights from early May to mid-July, peaking around June 20 to July 5.

What skipping the checklist can look like by late August

The worst plausible monsoon case is not one bug. It is three small problems you never saw, all showing up the same week. Picture a Tuesday in late August. The storm blew through at five, the street smells like wet creosote, and you are reading in bed when you notice a few pale insects with see-through wings on the windowsill. Then a dozen. Then a little drift of shed wings along the baseboard.

That windowsill matters. AZ1369 says desert subterranean swarmers are rarely found inside buildings, so when they come out of your bedroom wall, the colony that raised them is close: under the slab, in the framing, a few feet from your pillow. It has been eating since spring, behind drywall you never had a reason to tap. Your homeowners policy will not bail you out, either. The Insurance Information Institute says standard policies do not cover damage from termites or other pests.

Out in the side yard, the saucer under the potted bougainvillea has held rainwater since the weekend, and AZ1221 warns that stagnant monsoon water can turn out mosquitoes by the hundreds of thousands if the larvae get as little as three days. They find you at the patio table, around the ankles, exactly where the bulletin says Aedes aegypti likes to bite. Most bites just itch. But about one in 150 people infected with West Nile virus, AZ1221 notes, develops a severe infection of the brain or spinal cord.

And the bark scorpion that slipped under the worn garage door sweep in June has had all summer to explore. The UA scorpion team says they climb walls, cross ceilings and sometimes drop into beds and bathrooms. Something to think about at 2 a.m., barefoot, on the way down a dark hallway.

None of this is exotic. In Tucson it is just August with the chores skipped.

The checklist: before, during and after the storms

The Tucson monsoon checklist splits into three short lists, and the before list does most of the work. Print it, stick it on the fridge, and check it off twice a year.

Notice what is missing: sprays. Nearly everything on the list is about water, gaps and light, because those are the three things every monsoon pest is looking for.

How to work the checklist yourself

You can handle most of the Tucson monsoon checklist yourself with a caulk gun, a flashlight, a hose and two Saturday mornings, one in early June and one in October. In order of payoff:

• Seal from the ground up. The UA scorpion team says bark scorpions get in under doors and through weep holes, so start with door sweeps and weatherstripping, then caulk around pipes and eaves. Weep holes get coarse steel mesh, never caulk, because the wall needs to breathe. And respect your block wall: UA research found 95% of bark scorpions chose hollow block walls over every other refuge around a home.
• Shut down the mosquito nurseries. Tip every saucer, bucket, birdbath and toy twice a week, the interval AZ1221 calls ideal, and scrub the inside wall where the eggs stick. Clear the canales. Fix the dripping hose bib. Turn the wheelbarrow over.
• Keep water in every drain. Run the guest tub, the laundry floor drain and the casita sink weekly all summer. A full trap is a door a sewer roach cannot open, and our sewer roach guide goes through the house drain by drain.
• Change the porch light. Yellow bulbs draw fewer insects than white ones, according to UA Extension bulletin AZ1768, which leaves less prey at the door for scorpions. During the late June kissing bug peak, just leave it off. Our kissing bug control page covers what to do if they are already inside.
• Give the stem wall some air. AZ1356 asks for about four inches of bare stem wall between soil and stucco, soil graded away from the house, and shrubs and main irrigation lines at least 18 inches out. That decorative rock pile against the foundation looks great. Termites think so too.

After the last storm, walk the stem wall and garage with the flashlight for pencil-width mud tubes and tap the baseboards for a hollow sound. Our termite swarm season guide covers that check step by step.

When DIY is not enough

DIY is not enough once the signs point into the walls or under the slab, because a hose and a caulk gun cannot reach there. Watch for these five:

• Swarmers or piles of wings inside the house, on a sill, in a tub or along a baseboard.
• Mud tubes on the stem wall, a garage wall or a ceiling, or a tube you broke open that was rebuilt within days.
• Scorpions inside more than once a week after you sealed, or any in a bedroom or a child's room.
• Daytime mosquito bites that do not let up after two weeks of tipping containers. The source is somewhere you have not found, like a valve box or the neglected pool over the fence.
• Sewer roaches that keep coming with every trap in the house full. The door is a pipe you cannot see.

If one of those fits, the sensible next step is a phone call rather than another month of guessing. Call (888) 217-8578 and we connect you with a licensed local provider who can inspect the stem wall and slab, track down the entry point or breeding site, and treat with products labeled for that pest. Typical market ranges, not a quote: a termite inspection is often free with treatment and otherwise roughly $75 to $150, and a one-time mosquito barrier spray roughly $125 to $300. Our termite control page explains treatment, the mosquito control page covers seasonal plans, and our guide to pest control cost in Tucson puts every service side by side.

Why October is the easy part

October is the easy part of the Tucson pest year. The swarms are done, and a house that had its checklist worked is a dull place to be a bug. AZ1356 recommends a termite check in spring and again near the end of the monsoon anyway, so this is not a new chore. It is the same walk around the house with a better list. Do it, and the monsoon goes back to being what it should be: the best smell in the desert and a lightning show from the back porch.