2nd July, 2026
Why You’re Seeing More Ants Inside Your Home in Winter
Most Australian homeowners assume ant activity slows down in winter. After all, insects are supposed to go quiet when temperatures drop. So why are you seeing more ants inside your home in July than you did in January?
The answer is counterintuitive – and understanding it is the difference between fixing the problem and making it significantly worse.
Ants Don’t Slow Down in Winter. They Move Indoors.
Australian ant species, particularly black ants and coastal brown ants common across Victoria and South Australia, don’t hibernate. When outdoor temperatures drop and food sources on soil surfaces dry up, ant colonies don’t wind down – they relocate. And the warmest, most resource-rich environment within range of an established colony in winter is your home.
This is why winter ant activity inside Australian homes is a documented pattern, not an anomaly. The colony isn’t new. It was already in your garden or under your path. It simply moved its foraging focus indoors once outdoor conditions became less hospitable.
What ants are looking for in a winter home isn’t just food. It’s warmth and moisture. Your kitchen, laundry, and bathroom provide both. So does the space behind your dishwasher, under your hot water system, and inside your wall cavities. These areas maintain warmth even when the rest of the house is cold.
Why DIY Baits from Bunnings Often Make It Worse
Walk into any Bunnings and you’ll find a row of ant bait products. They’re inexpensive, accessible, and seem logical – ants eat the bait, carry it back to the colony, colony is eliminated. Problem solved.
The reality is more complicated, and for many households, DIY baiting actively worsens a winter ant infestation before it gets better.
Here’s why. Store-bought ant baits work on a specific mechanism – they rely on worker ants consuming the bait and returning it to the queen. This works reasonably well for small, surface-level colonies with a single access point. In winter, when an established colony has moved indoors and established multiple internal access routes through wall cavities and subfloor spaces, bait products encounter a completely different situation.
Multiple access points mean worker ants are entering your home from several locations simultaneously. A bait station placed near one entry point will attract and kill workers using that route – but it won’t reach the other entry points, and it won’t address the queen or the reproductive chambers of the colony. The result is that surface-level worker activity near the bait decreases while activity from other entry points continues or increases as the colony redistributes.
There’s a secondary issue too. Some DIY bait formulations cause colonies to split – a process called budding, where the colony divides and relocates to establish satellite nests. A colony that was in one location can become three or four separate colony clusters, each harder to eliminate than the original.
What Professional Treatment Addresses That DIY Cannot
Licensed pest control technicians approach a winter ant infestation differently to a bait station. The first step is identifying the species, which determines the correct treatment chemistry and approach – coastal brown ants, black ants, and fire ants all require different strategies. The second step is a full property assessment to identify all active entry points and determine whether the colony is established in wall cavities, subfloor spaces, or external nesting areas using the home for foraging.
Professional treatments for established internal infestations use registered products that transfer through the colony via contact and grooming behaviour – reaching the queen and reproductive chambers in a way that surface baits cannot. Entry points are also sealed or treated to prevent re-entry once the colony is eliminated.
Signs Your Ant Problem Has Moved From Garden to Structure
Not every ant sighting warrants a professional treatment, but certain signs indicate a structural infestation rather than a garden-level foraging problem:
- Ants appearing consistently inside regardless of how clean surfaces are kept
- Ant activity inside wall cavities – you can sometimes hear faint movement in walls at night
- Ants emerging from powerpoint covers or skirting board gaps
- Ongoing activity despite multiple DIY bait stations in place for several weeks
- Ants in areas with no obvious food source, such as bedrooms or living rooms
If any of these apply, the colony has established itself inside your home structure, and a professional assessment is the appropriate next step.
Frequently Asked Questions
Why do I have ants in my house in winter but not in summer?
Winter drives Australian ant colonies indoors in search of warmth and moisture rather than just food. Your home maintains a stable warm temperature that outdoor environments cannot offer during cold months, making it an attractive alternative nesting location for established colonies.
Do ant bait stations work?
They can work for small, garden-level infestations with a single access point. For established winter infestations where colonies have moved into wall cavities or subfloor spaces, store-bought baits typically address surface worker activity only and do not reach the queen or reproductive areas of the colony.
How long does professional ant treatment take?
A standard residential treatment takes one to two hours depending on property size. Most professional treatments provide significantly more effective colony elimination than DIY products because they use registered chemistry designed for structural infestations rather than surface-level bait.
Will ants go away on their own when the weather warms up?
Some foraging activity will move back outdoors in spring, but an established structural colony that has set up nesting sites inside wall cavities or subfloor spaces does not simply relocate back outside when the season changes.
If you’re seeing persistent ant activity inside your home this winter, the pattern is likely to continue without professional treatment. Our licensed technicians cover Melbourne, Geelong, and surrounding Victoria – and we can usually schedule within the week.
