Pest Control
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Most people expect ants in high summer. So a trail across the kitchen floor in January, or a handful of ants by the back door in early March, catches people out. There are two usual explanations, and telling them apart decides what you should do next.
Why ants appear early
Ants are cold-blooded, so their activity follows the temperature. Black garden ants, the species most likely to come indoors, spend the winter mostly inactive in the nest and become active as the soil warms, usually from around March. A spell of mild weather in late winter can bring workers out weeks earlier than usual.
A house is a good find for an early forager. It is warm, there is food on floors and worktops, and there is water at sinks, pet bowls and on condensation-damp windowsills. Kitchens and utility rooms are the usual hotspots, but ants can turn up anywhere food is eaten.
When early ants mean a nest indoors
If ants appear only on a warm afternoon and vanish again when it turns cold, the colony is most likely outdoors and has simply woken up early. If you are seeing ants most days through a cold spell, the nest is probably somewhere warm, and that can mean inside the building. Common places include:
- cavity walls, particularly near a boiler, flue or hot water pipes
- under suspended floors and behind kitchen units
- under a solid floor or a conservatory base, close to underfloor heating
- gaps in brickwork or around window frames on a sunny wall
Watch where the ants go once they have picked up food. If the trail leads to a skirting board, a crack in the floor or a gap around a pipe, rather than to an outside door, the nest may be in the structure.
Ants that live indoors all year
A few ant species found in the UK cannot survive outdoors through a British winter and live only in heated buildings. The best known is the Pharaoh ant: very small, around 2mm, and pale yellowish-brown. The ghost ant, smaller still with a pale, almost see-through body, is another. These are more often a problem in larger heated buildings such as hospitals, blocks of flats and commercial premises, and they nest in wall voids, behind fittings and near warm pipework.
Tiny pale ants indoors in mid-winter are worth getting identified. Home treatments can make them worse, because colonies with many queens can split and spread when disturbed.
Why it pays to act early
Early in the season a colony is at its smallest and the foraging trails are new. Left alone, the colony grows through spring and summer, the trails become well used, and ants can spread to other rooms. Dealing with the problem in February or March is usually quicker than dealing with it in July.
What you can do
- Remove the attraction. Clear crumbs, wipe up sugary spills, empty the toaster crumb tray, keep sweet foods in sealed containers and lift pet food bowls between meals.
- Deal with moisture. Fix dripping taps and leaks under sinks, and wipe condensation from windowsills.
- Seal the gaps. Fill cracks around door and window frames, along skirting boards and around pipes.
- Avoid spraying the trail. Sprays kill the ants you see and leave the nest untouched. Repellents can push ants to a new route, and with some species they can split the colony.
These steps make your house less attractive, but they will not remove a nest. If the nest is outdoors and you can find it, the advice in our guide to black ants in the house applies.
When to call us
Call us if ants keep appearing through cold weather, if the trail seems to lead into a wall or floor, if the ants are very small and pale, or if they come back after you have cleaned up and sealed the gaps. We identify the species, trace the nest and treat the colony rather than the workers you can see. See our ant control page for how we work.