The SC Midlands Pest Calendar:
Month-by-Month Pest Activity for
Columbia Homeowners

A pest calendar written for a Chicago or Denver audience assumes three to five months of hard winter that kills off outdoor populations, stalls breeding cycles, and gives homeowners a genuine reprieve. Columbia gets no such break. Our average January low sits at 37°F — cold enough to feel like winter, but not cold enough to keep fire ants from returning to the surface on a warm afternoon, stop German cockroaches from reproducing in your kitchen, or prevent termites from feeding in the soil beneath your foundation. The pest species that matter in this region operate on a near-continuous cycle that rewards prevention and punishes people who wait until they see a problem.

What follows is a month-by-month breakdown of what’s actually happening with the most significant pests in the Columbia area, Blythewood, Chapin, Elgin, Irmo, Lexington, Cayce, and the surrounding Midlands communities throughout the year. Every entry is grounded in verified biology and regional data — not national averages. If you’re going to be prepared, you need to know what’s coming for this specific ZIP code, not a hypothetical homeowner somewhere in the middle of the country.

January

January feels quiet, but it isn’t. Raccoons are entering their breeding season right now — SCDNR confirms that breeding peaks in January and February in South Carolina — which means pregnant females are actively evaluating den sites. Your attic is warm, elevated, and sheltered. From a raccoon’s perspective, it’s a better option than a hollow tree. Squirrels are in their first breeding window as well, with females beginning to seek secure nesting locations ahead of February and March births.

Rodents that found their way inside during the fall are fully established by now. They’re breeding, foraging nightly, and leaving behind gnawed wiring, contaminated insulation, and droppings that concentrate allergens in the air your family breathes. Termites aren’t swarming, but they’re feeding — eastern subterranean termite colonies work continuously through the soil regardless of surface temperature, consuming wood fiber in your substructure seven days a week. January is a good month to schedule a wildlife removal evaluation if you’ve heard scratching overhead or noticed soffit damage.

February

February is when the first eastern subterranean termite swarmers begin appearing in the Midlands, and homeowners are almost always caught off guard by it. Clemson Extension confirms the swarming window opens in February and runs through May, triggered by warm days following rainfall — specifically afternoons when temperatures climb above 70°F with high humidity after recent rain. You don’t need a 75°F day for a swarm. A sunny afternoon in the upper 60s after a good overnight rain is enough. The first swarmer you find on a windowsill in February isn’t a fluke. It’s the beginning of the most active termite inspection season of the year.

Raccoon denning pressure peaks this month. Females are heavily pregnant and actively breaking into attics through soffit gaps, roof returns, and damaged fascia — they only need about a 4-inch opening. Once a female gives birth in your attic in March or April, removal becomes significantly more complicated because the young must be located and removed separately. Getting ahead of it in February is the right move.

March

March brings the pest calendar to life in a hurry. Eastern subterranean termite swarming intensifies through the month, and March and April represent the peak of the swarming season in the SC Midlands. Any afternoon with sun, temperatures above 70°F, and recent rain is a potential swarm event. This is when most homeowners see swarmers for the first time — the winged reproductives that emerge from the soil and attempt to establish new colonies. Finding swarmers in or around your home doesn’t automatically mean your house is infested, but it does mean you have active colonies nearby and warrant a professional termite inspection before the season progresses. According to Clemson Extension’s termite resources, South Carolina’s warm climate and abundant moisture make it one of the highest-risk states in the country for termite damage.

Fire ants are back at the surface as March soil temperatures consistently reach 65–70°F. After a winter spent deeper in the soil, mounds rebuild quickly in warm weather. Mosquito season begins its early phase in March — not peak activity, but the first breeding cycles are underway in standing water anywhere it collects: clogged gutters, low spots in lawns, birdbaths, flower pot saucers. Wildlife birth season is also in full swing, with raccoon young arriving in late March.

April

April is the heaviest month on the pest calendar. Eastern subterranean termite swarming peaks across the Midlands, and call volume for termite concerns hits its annual high. If you haven’t had a termite inspection recently, April is not the month to delay.

Mosquito populations are building steadily. The Asian tiger mosquito — the aggressive, small, black-and-white striped species that bites during daylight hours — is the most common species in the Columbia area and has been documented in every South Carolina county. It overwinters as eggs that hatch with spring warmth and rain, which means populations can ramp up quickly when April brings consistent heat. Professional mosquito barrier treatment applied in April gets ahead of breeding cycles before populations establish in earnest.

Fire ants hit their peak surface aggression in April and early May as colonies rebuild. Mounds that appeared small in March are now significantly larger, with foraging workers covering a wide radius. Spring nuptial flights, where mated queens disperse to establish new colonies, typically occur in April through June following afternoon rains on warm days between 70–90°F. Every flight that goes unchallenged is a new colony establishing somewhere on your property or your neighbor’s.

May

Formosan subterranean termites add a second layer of swarming pressure beginning in May, and this is something that wasn’t a meaningful concern for most of the Midlands until relatively recently. Clemson Extension documented Formosan termites in both Richland and Lexington County as of December 2022, confirming their established presence in the Columbia area after decades of being predominantly a coastal species. The Formosan swarming season runs May through July, with peak activity in late May and June.

The critical difference between Formosan and native termite swarms is timing and behavior. Formosans swarm at night — from dusk until around midnight — and are intensely attracted to light sources. If you see large numbers of winged insects swarming around your porch lights or streetlights on warm May evenings, that warrants attention. Formosan colonies are significantly larger and more destructive than native species, capable of causing structural damage in a fraction of the time.

Mosquito season is now fully active. Flea and tick pressure is escalating as temperatures stay consistently warm. Anyone with dogs or cats that spend time outdoors is dealing with flea season from this point through September.

June

June is peak pest month across the board. Formosan termite swarming continues through the month. Mosquitoes reach their highest activity level of the year, with daytime populations driven primarily by Asian tiger mosquitoes and evening/nighttime activity from southern house mosquitoes and the malaria mosquito (Anopheles quadrimaculatus), which overwinters as adult females in protected sites like crawlspaces and storm drains and is active throughout the warm season. West Nile virus, transmitted by Culex species, is the most significant documented mosquito-borne disease risk in this region — in 2022, SC Department of Public Health confirmed 11 human West Nile cases statewide, with 6 in Richland County alone. Mosquito pressure in June is a genuine health consideration, not just a nuisance.

Fleas are at their worst during the hottest, most humid weeks of summer. A single female flea can produce up to 50 eggs per day, meaning an untreated infestation grows exponentially once established. Tick activity is high as well — Lone Star ticks and American dog ticks are the most commonly encountered species in the Midlands.

July

July is the hottest month in Colombia, with average highs around 95°F. Mosquitoes remain at peak or near-peak activity. Formosan termite swarming winds down by mid-to-late July. Fire ants are still active but shift to evening and nighttime foraging during the most extreme afternoon heat. Flea pressure stays high.

The second squirrel litter of the year is in progress, with births occurring in July following June breeding. These juveniles will be ready to disperse in late August and September, feeding directly into the fall period when squirrel intrusion calls peak.

August

August brings no meaningful letup in mosquito pressure — populations stay high through the month. Fire ants remain active and aggressive. Second-litter squirrel juveniles begin dispersing and exploring territory by late August, which is when attic entry attempts typically begin for this cohort.

Late summer also marks the beginning of wasp and yellow jacket population peaks. Colonies that started in spring have had all summer to grow, and by August, they reach maximum size. Disturbing a ground nest while mowing or a paper wasp nest under eaves generates a more severe response in August than it would have in May, simply because colony size is dramatically larger.

September

Mosquito season starts declining in September, but it isn’t over. The Asian tiger mosquito remains active through October in Columbia, and residents near Lake Murray or along the Congaree corridor, where standing water persists longer, typically see mosquito pressure extend further into fall than drier neighborhoods. Calling mosquito season over in September is premature in this climate.

Yellow jackets and ground-nesting wasps hit peak aggression in September as colonies sense the approaching end of the season and foraging workers defend resources more intensely. Snake encounters near homes increase in fall — copperheads, the most common venomous snake in the Columbia area, switch from nocturnal summer patterns to daytime activity as temperatures moderate, and they’re actively moving toward brumation sites in October. Seeing a copperhead in your yard in September or October isn’t unusual; they’re in transit, not established.

October

October is when two of the most consistent fall pest trends arrive simultaneously: palmetto bugs move indoors, and rodents begin their seasonal migration inside. Both are driven by the same trigger — nighttime temperatures dropping consistently below about 68°F, which happens in late September and early October in the Columbia area.

The American cockroach, universally known here as the palmetto bug, thrives in Columbia’s warm, humid summers and lives in mulch beds, storm drains, leaf litter, and sewer systems. When nights cool, they begin seeking indoor environments through gaps at pipe penetrations, around utility lines, and under exterior doors. October service calls for palmetto bugs spike reliably every year. Mice and rats follow the same logic — they don’t hibernate, but they strongly prefer warm indoor environments and begin testing entry points at your foundation, roofline, and utility penetrations as temperatures drop.

November

By November, palmetto bugs and rodents are in full indoor mode. German cockroaches, which are a separate problem from palmetto bugs and are entirely year-round indoor pests, may be discovered during fall cleaning as their populations spread within the walls and cabinets of infested kitchens. Unlike American cockroaches, German cockroaches never live outdoors — outdoor temperature has zero effect on them. A German cockroach infestation discovered in November didn’t just arrive; it’s been building undetected for weeks or months.

Wildlife activity shifts toward established den sites as temperatures drop. Opossums — poorly cold-adapted animals with exposed feet, tails, and ears vulnerable to frostbite — begin spending more time under decks, in crawlspaces, and occasionally in attics and garage storage as temperatures fall. Unlike raccoons, they aren’t damaging in the same structural sense, but they carry diseases and create odor and sanitation issues.

December

December doesn’t mean pests go away in Columbia. It means the pressure shifts entirely indoors. Rodents that entered in October and November are now fully established, reproducing, and working their way deeper into your home’s envelope. Termites feed underground, unaffected by surface temperatures. German cockroaches and stored product pests — flour beetles, pantry moths, grain weevils — are at home in your kitchen cabinets regardless of what the thermometer reads outside.

The trap homeowners fall into is treating December as a true off-season and letting prevention lapse until spring. By the time you see a problem in February or March, it’s been developing for months.