Why San Jose colonies sometimes last more than one year
In most of the country a wasp nest is an annual event. Frost kills the workers and the founding queen, only mated queens survive, and the paper is never reused. San Jose is one of the places where that rule bends. UC IPM is explicit about it: in very mild winters, or in coastal California south of San Francisco, some yellowjacket colonies survive for several years and become quite large. With winter lows averaging 42 degrees, this city rarely delivers the sustained freeze that ends a colony outright, particularly for a nest inside a heated wall. The consequence is arithmetic. A normal colony spends April through June with a single queen doing everything, which caps how big it can get by fall. A carryover colony starts the season with thousands of workers and no founding bottleneck, so it grows to the top of the UC IPM range rather than the middle. Practically, this means two things. A nest that looks large for the calendar deserves a professional look, and a nest you decide to ignore in October may not disappear on its own the way it would in Sacramento or Reno.
The nest inside the wall is the San Jose problem
Yellowjackets in a lawn are dangerous but at least they are outside. The version that causes the most expensive trouble in this city is the one inside the structure. UC IPM notes the German yellowjacket is becoming more common in urban areas of California and frequently nests in houses. In practice that means a colony behind stucco, in a soffit cavity, or in an attic corner, entering through a crack, a weep opening, or the seam where the soffit meets the fascia board. The trouble is that you cannot assess it. You cannot see the comb, you cannot count workers, and you often cannot tell whether the hole you found is the only one. Meanwhile, a colony that outgrows its cavity chews outward through whatever is thinnest, and interior drywall is usually thinner than exterior stucco. Two rules follow. Never plug the entrance while wasps are alive, because trapped workers move laterally and find the inside of the house. And do not spray a foaming product into a wall from outside, since it can push wasps into a bedroom rather than kill them where they are.
A month-by-month wasp calendar for San Jose
February and March are quiet queen months. Mated females come out of overwintering and begin small combs alone. Nothing is visible from a distance, and this is the cheapest possible moment to intervene if you happen to spot one. April through June is the build phase. The first workers take over foraging, the queen becomes a full-time egg layer, and the nest grows steadily. Prey is abundant because the winter rains have already produced a flush of insects, and with 82 degree average summer highs the colony is never heat-stressed. July and August are when foraging shifts. The dry season has stripped free water out of the environment, so wasps start showing up at irrigation, pools, and pet dishes, and workers begin scavenging protein for themselves. September and October are peak. Colonies hold their maximum population and the wasps are least tolerant of interference. This is the stretch when a backyard gathering attracts a dozen wasps in ten minutes. November onward is where San Jose diverges from most cities. The colony may wind down, or it may simply slow and continue.
What a first visit should include
The visit that goes well is mostly observation. A technician who knows wasps stands back and watches where the traffic actually goes for several minutes before touching anything, because a stream of wasps entering a stucco crack tells you nothing about where the comb hangs behind it. The inspection should cover the roofline, the soffit and fascia joint, gable and attic vents, weep openings and control joints in stucco, utility penetrations, the foundation line, and the base of any shrub or planter bed where a ground entrance could hide. On a property with fruit trees, the trees and the fence line deserve a walk too. Treatment on a hidden colony is a dust into the entrance, applied at dusk or after dark. It looks like almost nothing happened. Traffic tapers across the next day or two, and an honest close-out is a follow-up look rather than a same-day declaration. Before work starts, settle two questions. Is nest removal included after the colony dies, and is closing the opening part of the price or a separate item.
Renters, landlords, and a nest in a San Jose rental
A nest inside the building envelope is generally the landlord's expense, because the wasps got in through a building defect: a torn vent screen, a widened stucco crack, a gap at the soffit. Those are maintenance issues, not housekeeping. A paper wasp comb on a balcony umbrella the tenant bought is a fairer thing for the tenant to handle, and with 15 to 200 wasps in that kind of colony, it is a realistic thing to ask of someone. Put the request in writing the same day. Note where the wasps enter, roughly how many per minute you count going in and out, whether anyone in the unit has a sting allergy, and whether the wasps are appearing indoors. That last point moves it from a nuisance report to a habitability issue. Do not treat a wall void yourself in a rental. Beyond the sting risk, drilling or foaming into stucco is damage you may be billed for, and in a market where the median home value runs around $1,350,000, that repair is not cheap.
Comparing two wasp quotes in San Jose
The lower number usually describes a smaller job, so line the quotes up on scope before you look at price. Start with coverage. One quote may address the single nest you pointed at, another may include a full structural inspection with any additional colonies found. On a lot with mature fruit trees, finding a second nest is not unusual. Then check nest removal. Killing a colony inside a wall and physically extracting the paper are separate labor, and a large dead nest can stain drywall and draw secondary insects as it breaks down. Then ask about the callback in plain terms. If wasps are using that opening again in two weeks, does someone return, at what cost, and for how long does that hold. Given that colonies here can persist through winter, the length of that window is a more meaningful question than it would be in a cold-winter city. Finally, confirm the license yourself through the state pesticide agency directory rather than accepting a number read to you over the phone.