This calendar is general, not a local schedule. Its one firm pattern is the tick season: adults are most active from late fall through spring and nymphs from spring into early summer. Other pests are described by general habit only, because no month-by-month timing for Anderson Valley has been documented.
Key takeaways
- The one seasonal pattern on this page with a source is the western blacklegged tick: adults in late fall through spring, nymphs in spring and early summer.
- Termite swarms often follow the first fall rains in parts of California, but no North Coast timetable is established, so none is printed here.
- Wasp and yellowjacket activity builds through the warm part of the year, and local nest timing is not documented.
- Rodents and ants respond to weather and food, and their timing changes from one building to the next.
- Use the calendar to decide when to look harder, then ask a technician to check the site rather than relying on the table.
Why is this calendar mostly about ticks?
Ticks are the only pest on this site with a seasonal pattern drawn from a source. Every other row is general habit, and it is labeled that way so that it cannot be mistaken for a local timetable.
A seasonal calendar is only as good as its sources. For the western blacklegged tick, the Mendocino County public health guidance gives the pattern directly, and that is the spine of this page. For other pests, the sources on this site describe general habits and California-wide patterns, and they do not describe what happens in Anderson Valley month by month.
That gap is deliberate. A calendar that filled every row with a confident month would look helpful and would be invented. A homeowner who planned a termite inspection, a wasp removal or a rodent exclusion around a made-up date could be caught out. This page marks what is known and leaves the rest as general guidance.
The table below the sections sets out the general pattern in plain terms. Read it as a way to decide when to look harder, not as a forecast for your property.
What happens in late fall through winter?
Adult western blacklegged ticks are active in late fall through spring, so the tick risk does not stop in the cooler months. Winter is also when rodents tend to look for shelter, though the timing for this valley is not documented.
The county's tick pattern says adults are most active from late fall through spring. A walk through brush or long grass on a mild winter day can bring an adult tick into contact with a person or a dog. Many people stop checking for ticks when the weather turns cold, and that is the habit this season is most likely to break.
Rodent activity is a common concern in cooler months, because mice and rats look for warmth and shelter as temperatures drop. That is a general pattern and not a sourced local schedule. A rural home with a woodpile, an outbuilding or a crawl space gives rodents the shelter they seek, and it is worth checking those areas before the cold sets in.
Winter is also the season when the first heavy rains arrive, and Route 128 near Navarro is known to close in winter storms from flooding. Plans for inspections, removals or deliveries that depend on that road should allow for a closure.
What changes in spring and early summer?
Spring is when adult and nymphal ticks overlap, and nymphs are most active into early summer. It is the most important stretch for tick checks, because the nymphs are small and easy to miss.
The county pattern puts nymph activity from spring to early summer. That overlaps with the tail of the adult season, so a spring walk can bring both stages into contact. A nymph is much smaller than an adult, and a body check that only looks for large ticks can miss it. Checking the scalp, behind the ears and the lower legs is worth the extra minute.
Spring is also when many insects become active again. General pest patterns in California show ants and wasps becoming more visible as the weather warms, but the timing for any individual nest or trail in Anderson Valley is not documented here. Look for activity around the house, the garden and the woodpile, and note when it first appears.
For a household with pets, spring is a good time to review their tick protection with a veterinarian, because dogs that roam in brush or grass are exposed to the same ticks as people. That advice is general, and the veterinary team is the right source for the specifics.
When do termite swarms usually show up?
In many parts of California, termite swarms often follow the first fall rains. No North Coast swarm timetable has been set, so the swarm season for a specific property is unknown until someone sees it or inspects the building.
The University of California's guidance on termites says swarms often follow the first fall rains. Winged termites leave the colony when conditions are warm and humid, and a light autumn rain after a dry summer is a common trigger in many areas. That is the general pattern, and it is the only seasonal termite statement this calendar makes.
The table does not put a month against termite swarms for Anderson Valley, because the sources do not give one. A swarm seen in the valley should be photographed or kept, and the technician who inspects the building can judge what it means. The absence of a swarm in a given season does not show that a colony is not present.
Termite inspection does not have to wait for a swarm. A property with wood in contact with soil, a damp crawl space or a history of past damage can be inspected at any time of year.
When are wasps and yellowjackets active?
Wasps and yellowjackets build their colonies through the warm part of the year, and their nests are most noticeable late in the season. The University of California's Pest Notes cover them, but the local timing of nests in this valley is not documented.
Social wasps, including yellowjackets, build colonies during the warm months. A nest starts small in spring and grows through summer and into early autumn, which is why late-season nests are the ones most often noticed by people who walk past them. Yellowjackets are attracted to sugary food and to protein, and a backyard meal or a garbage can can draw them in.
The University of California's Integrated Pest Management Program publishes a Pest Note on yellowjackets and social wasps. It describes the general biology and the habits of these insects, and it is the right reference for the broad pattern. It does not provide a local nest calendar, and this guide does not invent one for Anderson Valley.
A practical habit is to check the usual nest sites in late spring and again in late summer. Look under eaves, in wall voids, under decks and in the ground along lawn edges. Finding a nest early is easier and safer than dealing with a large colony in the middle of the season.
Why are rodents and ants harder to time?
Rodents and ants respond to food, water, shelter and the weather at each individual building, so one calendar cannot predict them. Their general habits are well described, but their timing on a given property depends on the property.
Ants come indoors seeking food, water, warmth or shelter, or to escape dry heat or flooding. That list explains why a trail can appear in a kitchen after a hot spell, after a rainy week or after a pet food bowl has been left out. The cause is usually local, and the calendar cannot see it. The Argentine ant is the most common household ant in California, and it can travel up to about 100 feet to reach a building.
Rodents are present in almost every California city, and roof rats and Norway rats each have their own habits. Roof rats nest in shrubs and trees and favor attics and walls. Norway rats burrow along foundations and woodpiles. Mice are a separate question. The sources on this site do not document which rodents are active in Anderson Valley, so the table describes habits only.
A property owner who wants to know the timing for their own building is best served by a simple log. Note when ants, rodent signs or wasps appear, what the weather was like and what was happening around the house. After a year, the log will show more about that property than any general calendar.
How should I use a calendar like this?
Use the calendar to decide when to look harder for ticks and when to plan inspections, not as a forecast. Confirm any timing for your own property with a technician who has seen the site.
Start with the tick pattern, because it is the one part of the calendar with a source behind it. Put checks into your routine for late fall through spring for adults, and for spring into early summer for nymphs. Those are the windows when a body check and a clothing check are most worth doing after time outdoors.
For the other pests, use the general patterns to decide when to look, and treat any dates as a guide to your own observations rather than as a rule. A technician who inspects the building can tell you more than a table can, and the timing of a treatment or an exclusion depends on what is found.
If you want a firm answer for a specific pest on your property, the honest route is to describe what you have seen to a technician and ask what they would check and when. Calling (855) 974-4733 is the fastest way to start that conversation, and the technician can plan the visit around your site rather than around a generic month.
Frequently asked questions
When are ticks most active in Anderson Valley?
The county's pattern is that adult western blacklegged ticks are most active from late fall through spring, and nymphs from spring into early summer. The valley has no separate local timetable documented on this site.
When do termites swarm in Anderson Valley?
Swarms often follow the first fall rains in many parts of California, but no North Coast timetable has been set. A swarm you see is a reason to call for an inspection, not a date you can plan around.
Why is this calendar so short on other pests?
Because the sources on this site do not document month-by-month timing for ants, wasps or rodents in the valley. Rather than invent one, the page gives the general habit and says where the local timing is unknown.
How do I find out when pests are active at my property?
Keep a simple log of what you see, when, and the weather at the time, then share it with a technician. A year of notes tells you more about one building than any general calendar can.
Sources
- Mendocino County Public Health - Ticks and Lyme Disease
- University of California Statewide Integrated Pest Management Program - Pest Notes
This guide is general information for Mendocino County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.