Spider control across the Bay Area

Realistically one: the western black widow. It is the only spider native to the Bay Area whose venom is medically significant, and even then bites are uncommon and rarely serious in a healthy adult with modern care. They matter more for children, older people and anyone with an underlying condition. The brown widow has been spreading through California in recent years and its venom is weaker than the black widow's. Almost everything else you find around a Bay Area house, the orb weavers, wolf spiders, cellar spiders and jumping spiders, is not a medical concern, however unsettling it looks. We have more on identification in our guide to black widow spiders in the house.

No. Brown recluse spiders are native to the central and southern states, roughly Missouri through Arkansas and Tennessee, and decades of survey work has found no established population in California. Bites diagnosed here as brown recluse almost always turn out to be something else, usually a skin infection or a different insect bite. If you have found a small brown spider in the Bay Area it is very likely one of several ordinary species. Send us a photo and your technician can tell you what it is.

The mature female is the one to know: glossy jet black, about half an inch of body, with a red or orange hourglass on the underside of the abdomen. The web is the other tell, and it is often easier to spot than the spider. It is messy and irregular rather than the neat spiral people picture, and it is built low and out of the wind: under patio furniture, in a garage corner, around a hose bib, inside a water meter box, in a woodpile. Males and juveniles are smaller and lack the clear hourglass. If you think you have found one, leave it where it is and call us.

Two things, usually at once. Spiders follow food, so a lot of spiders means a lot of other insects you probably have not noticed. That is why the useful question is rarely "how do we kill these spiders" but "what are they eating". The second reason is seasonal: autumn is when males of several local species wander looking for a mate, which is why a big fast spider crosses the kitchen floor in September. We wrote that one up in why spiders come inside in the fall.

Three things, and the first one is mechanical. Every eave on the structure gets swept with an extension pole, at full length, whether or not webs are visible, and that takes the webs and the egg sacs with it. Then a perimeter treatment around the foundation, up to about eighteen inches on the structure, concentrated in the cracks and crevices. Then the insects the spiders are feeding on, because that is what decides whether they come back. Sheds, detached garages and guest houses get the same treatment as the house.

Wind. Spraying up into an eave risks the application drifting where it should not go, so it is not something we do, on any property. The eaves get swept instead, which also removes the webbing and the egg sacs rather than leaving them in place. The sweeping heads themselves never get product on them either. If the structure is wet we skip the sweeping that visit, because sweeping a wet building just makes a mess of it, and inspect instead.

It helps more than people expect, because an egg sac left in a corner can hatch long after the spider that made it is gone. Clearing webs from eaves, porch corners, meter boxes and the underside of patio furniture is genuinely useful between visits. What it will not do by itself is change why the spiders are there, which is the insect population around the building and the lights that draw them in at night.

Some will. New spiders wander in from outside all year, and Bay Area neighborhoods with mature landscaping produce a lot of them. What a recurring plan changes is that the webs never get established, because the eaves are swept every visit and the perimeter is kept fresh. Most homes do best on a quarterly plan for that reason. If pests come back between visits on your recurring plan, we come back at no charge.

Because it is the most inviting habitat on the property: dark, undisturbed, a little humid, full of other insects, and full of stored boxes for those insects to live in. It also has the widest entry points on the building, the gap under the door and the vents. Clearing clutter and sealing those gaps does most of the work; adding the garage to the regular service does the rest. It is also the single most likely place on a Bay Area property to find a black widow, which is a good reason not to reach into a stored box by hand.

For the exterior work, only one thing, and your technician does it anyway: move what is stacked against the building, bins, shoes, toys, door mats, so the foundation can actually be treated. Interior treatment is available on request rather than standard, and if you want it, pull furniture away from the walls in those rooms and plan on nobody being in a treated room for an hour, people and pets both.