How to Tell If You Have Termites — the Early Warning Signs Sydney Homeowners Should Watch For

Termites work hidden. Most of the damage they cause — eaten-out timbers, hollowed bearers, galleries running through structural framing — is invisible until something fails. A sagging floor. A door that doesn't close right. A section of wall that sounds wrong. By the time those visible signs appear, the damage behind them is already done.

What homeowners can catch are the earlier signals: the signs termites leave when they're foraging, when a colony is sending out reproductives, or when conditions inside a wall shift in ways that show up on the surface. None of these are diagnostic on their own. But any of them in combination — especially after a wet period — is worth taking seriously.

Mud tubes on walls, piers, or slab edges

Mud shelter tubes are a direct physical indicator of subterranean termite activity. Of the signs in this list, they're the one inspectors look for first. Termites are soft-bodied insects that desiccate quickly if exposed to open air. To travel above ground or across surfaces, they build enclosed tubes from soil, saliva, and other material — typically 10–20mm wide, brown to dark grey, with a rough texture.

Where to find them:

• Subfloor brick piers. If your home has a raised subfloor, look at the vertical surface of the piers. A mud tube running from the soil up the side of a pier — not a mark on the brick, but a raised earthen construction — is one of the more reliable indicators of active subterranean termite ingress.
• Foundation walls. Along the outside base of your home, particularly in areas where soil is close to the brickwork or timber.
• Slab edges. Where the edge of a concrete slab is visible at ground level, look for tubes running up and over the concrete face. This is why the 75mm inspection zone matters — if you can see the slab edge, you can see a tube before it reaches your framing.
• Internal walls near wet areas. Less common, but tubes can appear on internal plaster near bathroom or laundry cavities if a colony has established access through the subfloor.

Mud tubes don't always mean active infestation. Old, dried, hollow tubes indicate past activity that may or may not have been treated. Fresh, solid tubes with earthen material intact indicate activity now. An inspector can check whether a tube is live within minutes.

Hollow-sounding timber

Subterranean termites eat timber from the inside out, leaving a thin intact shell of paint or veneer over a hollowed core. The exterior surface can look completely normal. The timber underneath is largely gone.

The test: run your knuckle firmly along skirting boards, door frames, and any structural timber you can access. Healthy timber produces a dense, flat knock. Hollowed timber produces a papery, resonant sound — as if you're tapping on cardboard backed by air. The difference is immediately recognisable once you've heard both.

Areas worth checking:

• Skirting boards near bathrooms, laundries, and anywhere regularly exposed to moisture — these are the first areas affected when termites enter via wet conditions.
• Door frames and window architraves, particularly in older homes where the framing is timber-to-plaster.
• Floor timbers near external walls. Press lightly on timber floor sections that feel soft or slightly springy — they shouldn't feel that way in a sound floor.

Hollow sound by itself is not always termites. Old plaster can delaminate; timber can crack or separate. But hollow timber near a wet area, or near any of the other signs below, is worth flagging for a proper inspection.

Frass on the floor — termite or ant?

A common homeowner panic moment: fine dust or debris appearing on the floor near skirting boards, on windowsills, or below ceiling cornices. The instinct is to assume termites. Most of the time, it's not.

Ant frass is fine, black, and dusty — like ground pepper. It falls in small loose piles near ant entry points. If you see fine black dust, look for ant trails in the same area.

Termite frass and workings are brown mud, solid in texture — not powder, not dust. You might find brown mud-like material pushed out of small openings in timber, or packed into crevices. It doesn't crumble into fine powder when you touch it.

Borer frass is a third option worth knowing: very fine pale or buff-coloured powder falling from small round exit holes in timber. If there are visible holes in the timber with fine dust below, borers are more likely than termites.

If what you've found is fine, black, and dusty: that's almost certainly ant activity. Not good, but manageable and not structural. If it's brown, muddy, and solid: treat that as a reason to call an inspector — that's termite workings.

Doors and floors that have shifted

Termites damage the structure of walls, door frames, and floor systems. One visible downstream effect is movement that appears when you go to open a door or walk across a floor.

Sticking doors or windows. When termites damage the timber framing around a door opening, the frame can distort. The door was fitted when the frame was sound — now the opening has changed shape. Sticking doors or windows in areas that have never had a moisture problem are worth noting.

Sagging floors. A floor that has developed a soft spot, a bounce when walked on, or a perceptible sag is often showing the first structural sign of damage to the joists or bearers beneath. This is a late-stage indicator — if the floor is sagging, the damage has been progressing for some time.

Paint blistering over a flat surface. Where termites have eaten up behind painted surfaces, the paint can blister or lift in a bubble-like pattern. This is different from normal paint failure, which tends to crack, flake, or chalk. Blistering over a flat area of wall or door frame, especially in an older home, is worth pressing lightly — if it sounds hollow, that warrants investigation.

Swarmers near windows in spring

Each spring, mature subterranean termite colonies release winged reproductive termites — called alates or swarmers — to establish new colonies. Swarmer flights typically occur on warm evenings following rain, and the insects are drawn to light. Finding a cluster of winged insects near an indoor light source or on a windowsill is one of the more reliable seasonal signals.

Swarmers don't indicate that your home has been infested. They do indicate that a mature colony is established within foraging range of your property, typically within a few hundred metres. That is information worth acting on.

Telling swarmers apart from flying ants (they look similar):

• Wings: Termite swarmers have two pairs of equal-length wings. Flying ants have unequal wings — the front pair is noticeably larger.
• Antennae: Termite antennae are straight. Ant antennae are elbowed, with a distinct bend near the base.
• Body shape: Termites are thick-bodied, uniform in width. Ants have a narrow pinched waist.

After swarmers land, they shed their wings. A cluster of shed wings on a windowsill on a warm spring evening is itself a signal. If you find shed wings inside your home — not outside — the source is close.

When to call

Any one of these signs, in isolation, may have an innocent explanation. In combination, or following any of them in an older home with known moisture history, the threshold for calling an inspector is low. Here's the honest version:

If you've found a mud tube, hollow timber near a wet area, or shed wings inside the house: call now.

If you've noticed a sticking door or blistering paint but nothing else: note it, check for the other signs listed here, and book an inspection if you can't rule termites out.

If you haven't found any of these but your home is more than 20 years old: an annual inspection is the appropriate response. Some things you can't see from outside the walls, and that's exactly the job of the inspection — to check the things you can't check yourself.

Book a termite inspection — or a pre-purchase inspection if you're in the buying process.

If you've spotted any of these — I'll come and have a look

If something in this list has matched what you've found, the best next step is a proper inspection. I use a thermal imaging camera and moisture meter on every job — both of which pick up what a visual-only check misses. If it turns out to be nothing structural, I'll tell you that directly. If there's something there, you'll know what it is and what the options are.

Book at activetermitecontrol.com.au or call 0405 790 927. I'll give you a straight picture of what's there.