Seasonal Pest Calendar: What Shows Up When and What to Do

Pests follow the weather. The ants marching across your counter in April, the mosquitoes in July and the mice in the garage in November are all responding to temperature, rain and the food available outside. If you know what to expect each season, you can do the right prevention job a few weeks before the pests arrive instead of reacting after they move in. This calendar covers the US as a whole, so adjust the timing for where you live.

A note on regional timing

The seasons below are a rough guide. In the South and along the Gulf Coast, spring pests appear earlier, summer pests last longer and some never fully go quiet in winter. In the North and at higher elevations, the active season is shorter and the fall push indoors starts earlier. Your county extension office can tell you what is typical where you live.

Pest calendar at a glance

Spring

What to expect. Warmer temperatures and spring rain trigger winged termites (“swarmers”) to fly from established colonies. Ants swarm around the same time, which is why the two are often confused. As the weather warms, ants also start foraging in kitchens, and insects that spent the winter in your walls and attic start to reappear indoors.

What to do.

• Look closely at any winged insects inside, especially near windows and doors. Winged termites found indoors almost always mean an infestation that needs treatment. Our guide to the signs of termites shows how to tell them from flying ants.
• Do not panic. Swarmers do not damage wood and die within about a day. Vacuum them up, save a few in a sealed bag for identification and take your time getting inspections.
• Notice where swarmers come from. A swarm from a tree stump or woodpile out in the yard does not by itself mean the house is infested. Swarmers coming up beside the foundation or from an attached porch or patio are a stronger sign that the house needs an inspection.
• Clean up ant food sources and caulk the entry points you find. See our ant control guide.
• Check for moisture. Clean gutters, check downspouts and fix leaks found during spring rains.
• Repair window and door screens before you start opening windows.

Summer

What to expect. Mosquitoes breed in standing water, and ticks are most active from April through September. Wasp and yellowjacket nests grow through the summer. Fleas can build up in homes with pets.

What to do.

• Dump standing water once a week. Empty, scrub, turn over, cover or throw out anything that holds water: buckets, plant saucers, bird baths, old tires, kiddie pools and trash can lids. Check indoors too.
• Use an EPA-registered insect repellent when you spend time outdoors, and follow the label.
• Check for ticks after time in grass, brush or woods. Shower within two hours of coming inside, check your whole body and check children and pets. Ticks can ride in on gear and coats.
• Keep the yard less tick-friendly by mowing often, removing leaf litter and cutting back tall grass and brush near the house.
• Watch for nests under eaves, in sheds, in decks and in the ground. Our guide to wasps, hornets and yellowjackets covers when to leave a nest alone and when to get help.
• Keep up with flea prevention your veterinarian recommends for your pets. If fleas get into the house, see our flea guide.

Fall

What to expect. As nights get colder, mice move into buildings. Boxelder bugs, multicolored Asian lady beetles and brown marmorated stink bugs gather on sunny, south- and west-facing walls and squeeze into gaps to spend the winter inside walls and attics.

What to do.

• Seal up early, in late summer or the first cool weeks of fall, before insects and rodents start looking for shelter. Check windows, doors, siding, eaves, soffits and gaps around pipes, wires and chimneys.
• Fit door sweeps and repair screens. A 1/4-inch gap is enough for a mouse.
• Use materials mice cannot chew, like metal, hardware cloth, concrete or coarse steel wool. Our rodent-proofing guide explains how.
• Move firewood away from the house and bring in only what you will burn soon.
• Vacuum overwintering insects that get inside, then empty the vacuum into a sealed bag or a bucket of soapy water. Stink bugs and lady beetles release a smell when crushed, so a cheap separate vacuum is handy. Perimeter sprays and indoor insecticides are often not effective for these insects.
• Store birdseed, grass seed and pet food in lidded metal or heavy plastic bins.

Fall sealing is the highest-payoff prevention job of the year. It keeps out mice and overwintering insects at the same time.

Winter

What to expect. Mice that got in during fall are active indoors. Indoor pests like cockroaches and pantry pests do not care about the weather outside, so they stay a problem in warm kitchens. Insects that moved into walls and attics in fall can turn up in living areas, and boxelder bugs stay tucked away until warm weather returns.

What to do.

• Inspect the attic, basement, garage and crawlspace for droppings, gnaw marks and nesting material. Our guide to signs of rodents shows what to look for.
• Set snap traps where you find signs. See our guide to getting rid of mice.
• Check stored food for pantry pests and keep it in sealed containers.
• Vacuum stray insects that wander into living areas rather than spraying.
• Make a repair list for spring: gutters, grading, screens and any gaps you found.

Seasonal questions

Do I need to spray my house every season? No. Routine spraying on a schedule is not needed for most homes. Sealing, moisture control and cleanup each season prevent most problems. See our integrated pest management guide for when treatment makes sense.

What is the best way to deal with stink bugs and lady beetles inside? Vacuum them up and drop them into soapy water. Avoid crushing them, since both release a smell. Sealing gaps before fall is the best way to keep the next wave out.