As temperatures climb in spring, several types of insects either wake up inside your walls or find new ways to sneak indoors. The most common culprits are stink bugs, cluster flies, ants, clover mites, and termite swarmers. Some of these were hiding in your home all winter and are now trying to get back outside. Others are newly active and looking for food, moisture, or a place to breed.
Overwintering Bugs That Wake Up Indoors
Some of the most alarming spring invasions aren’t new arrivals at all. Certain insects entered your home the previous fall, tucked themselves into wall voids, attics, and window frames, and spent the winter in a dormant state. When spring warmth reaches their hiding spots, they emerge in large numbers, often appearing suddenly around windows and light fixtures.
Brown marmorated stink bugs are one of the most recognizable. These shield-shaped, mottled brown insects typically emerge from hibernation between March and May. They’re drawn to warmth, so you’ll usually see them on south-facing walls or sunny windows first. They don’t bite or damage your home, but they release a pungent odor if crushed or startled. The best removal method is a vacuum cleaner, and emptying the bag immediately afterward keeps the smell from lingering.
Cluster flies follow a similar pattern. About 3/8 inch long and dark gray, they look like house flies but move more sluggishly. They aren’t attracted to garbage or rotting food. Their larvae actually develop as parasites of earthworms in the soil, so their life cycle has nothing to do with your kitchen. They entered your home in late summer, typically through south-facing walls warmed by the sun, and packed into attics and wall voids. In spring, they stir and drift toward windows and lamps in noticeable clusters.
Boxelder bugs and lady beetles (often the multicolored Asian variety) round out the overwintering group. Both congregate on warm exterior walls in fall, find cracks to slip through, and reappear indoors when spring temperatures rise. None of these overwintering pests breed inside your home. They’re simply trying to leave.
Clover Mites: Tiny Red Dots on Windowsills
If you’re finding pinpoint-sized reddish or greenish specks crawling on windowsills, walls, or curtains, you’re likely dealing with clover mites. At just 0.75 mm long, they’re one of the larger plant-feeding mites but still barely visible. Their most distinctive feature is an unusually long front pair of legs that extends forward, which you can spot with a magnifying glass.
Clover mites feed on grass, clover, and other plants outside. They migrate indoors during spring when populations boom in well-fertilized lawns, especially on the sunny side of a building. They don’t bite, don’t carry disease, and can’t survive long indoors. The real nuisance is that crushing them leaves a reddish-brown stain on surfaces. Use a vacuum to remove them rather than wiping, which avoids the staining entirely.
Ants and Termite Swarmers
Spring is peak season for ant colonies to expand, and you’ll often see scout ants trailing along baseboards, counters, and door frames looking for food and water. Small black ants and odorous house ants are the most frequent indoor visitors, drawn by crumbs, pet food, and moisture near sinks. Cleaning up food sources and sealing entry points usually resolves a minor ant problem quickly.
More concerning are the winged insects that appear in small swarms near windows or light sources in spring. These could be flying ants or termite swarmers, and telling them apart matters. Termite swarmers have straight, bead-like antennae, a thick waist with no pinch, and two pairs of wings that are equal in length. Flying ants have elbowed antennae, a narrow pinched waist, and wings of unequal length (the front pair is noticeably larger). If you’re seeing equal-length wings and thick waists, that’s a sign of a termite colony nearby, and it’s worth getting a professional inspection. A swarm inside the house specifically suggests the colony may be in or under the structure itself.
Other Common Spring Invaders
Carpenter bees become active in spring, drilling perfectly round holes (about the diameter of a finger) into unpainted or weathered wood on decks, eaves, and fascia boards. You’ll notice them hovering near wooden structures. Males are territorial and may buzz close to you, but they can’t sting. Females can sting but rarely do.
Centipedes and silverfish also become more visible in spring, though they may have been present year-round. Both prefer damp areas like basements, bathrooms, and laundry rooms. A spike in centipede sightings often signals a moisture problem or a food source, since centipedes eat other insects. Reducing humidity with a dehumidifier can make these spaces far less hospitable.
Fruit flies and fungus gnats also pick up in spring, breeding in overripe produce, compost bins, and the moist soil of houseplants. Removing their breeding source is the only lasting fix.
How to Keep Spring Bugs Out
Physical exclusion is the most effective long-term strategy. That means sealing every gap bugs could use to enter. The specifics matter more than people realize.
For cracks and gaps up to 1/4 inch, standard caulk works. For larger openings, use a flexible elastomeric sealant that can stretch without cracking as your home expands and contracts with temperature changes. Hairline cracks and porous surfaces benefit from a liquid sealer. Pay special attention to where utility pipes, wires, and vents penetrate exterior walls, and seal around window and door trim from the inside as well.
Doors are a major entry point. The gap between the bottom of an exterior door and the threshold should be less than 1/4 inch. If it’s larger, install a tight-fitting door sweep that extends the full width of the door and brushes the ground. Metal-and-rubber sweeps are the most durable option.
Window and door screens block most household pests at standard mesh sizes. A typical window screen (16 to 18 mesh) stops house flies, fruit flies, and most crawling insects. Mosquitoes require at least 14 to 18 mesh depending on the species. If you’re dealing with very small biting flies or gnats, you may need finer mesh in the 30 to 50 range, though that also reduces airflow.
Managing Bugs Already Inside
For overwintering pests like stink bugs, cluster flies, and lady beetles, removal is straightforward: vacuum them up. They aren’t reproducing inside your home, and they’ll stop appearing once the group that overwintered has either escaped outdoors or died. Sealing interior gaps around window casings, baseboards, and light fixtures can limit how many reach your living space from wall voids and attics.
For pests that are actively entering from outside, like ants and clover mites, focus on the conditions attracting them. Clean up food residue. Fix leaky faucets that create moisture. Pull mulch and dense vegetation back from your foundation by at least several inches, since these create bridges for insects to reach your walls. A gravel strip between landscaping and the house discourages clover mites especially.
Pesticides work best as a targeted last resort, not a first line of defense. If you do use them, spot treatments along specific entry points are more effective and safer than broad spraying. Bait stations for ants, for example, let foragers carry the product back to the colony rather than just killing individual scouts. The goal is always to address why bugs are getting in, not just to kill the ones you can see.
When the Problem Points to Something Bigger
Most spring bugs are nuisance pests. They’re annoying but harmless to your home and health. The exceptions worth taking seriously are termite swarmers (which signal an active colony), carpenter bees or carpenter ants (which can damage wood over time), and any pest appearing in large, repeated numbers after you’ve sealed entry points. Persistent indoor ant trails, for instance, can indicate a nest inside a wall rather than visitors from outside. A sudden appearance of many winged termites indoors is never something to wait on.