The two that matter
Western black widows are common across Pima County. Look for a glossy black body, a red hourglass on the underside of the abdomen, and a messy, irregular web low to the ground — under patio furniture, in block wall voids, inside meter boxes.
Arizona recluse spiders exist here but are far less common than is widely assumed. They are uniformly tan with a violin-shaped marking and six eyes in three pairs. Most reported recluse bites in Arizona are misidentified.
The ones that look scary but aren't
Giant crab spiders, tarantulas, wolf spiders, and jumping spiders are all common in the Tucson valley and none pose meaningful danger to people or pets. They are also effective predators of the insects you actually want gone.
How to reduce spider pressure
De-web monthly, especially eaves, patio corners, and block wall seams. Egg sacs left in place hatch hundreds of spiderlings.
Control the food source. A general pest program that reduces crickets, moths, and flies will do more for your spider population than spraying spiders directly.