Ants Identification Greenwich: What Signs Should You Look For?

The Trail

What to look for: a consistent line of ants moving in both directions along the same route, typically hugging an edge - a skirting, a worktop join, the line where a wall meets a floor, the frame of a door.

What it tells you: more than anything else. Ants lay a chemical trail between food and nest and follow it faithfully, so the line is a map. Follow it to where it leaves the building and you are within a metre or two of the nest.

What it rules out: individual ants wandering with no pattern are foragers exploring, and may have nothing to do with your property. The consistency is the signal, not the number.

Excavated Soil

What to look for: small piles of fine, loose, crumbly soil pushed up between paving slabs, at the edge of a path, on a doorstep, at the base of a wall or through a crack in concrete. Often fresher and finer than surrounding soil.

What it tells you: the nest is directly beneath, and it is active. This is the clearest external sign there is, and pointing at it when we arrive saves a great deal of time.

What it rules out: worm casts are larger, wetter and more granular. Mole activity is on an entirely different scale.

Where the Nest Will Be

What to look for: ants prefer dry, workable, well-drained ground with something warm above it. In practice that means:

• Under paving slabs, a path or a patio.
• Beneath a doorstep or a concrete threshold.
• Against the base of an external wall, particularly a sunny elevation.
• In made-up ground where levels have been raised over the years.
• Under decking, in a bank of soil, or beneath a shed base.
• Occasionally in a cavity wall or under a floor, which is the version that produces year-round indoor activity.

The Ants Themselves

Black garden ant

What to look for: dark brown to black, the familiar ant of British gardens. Nests outdoors in soil and under hard surfaces, comes indoors to forage, and is most active in warm weather.

What it tells you: that this is the ordinary version of the job - an outdoor colony with a route in, treatable by baiting the trail so the workers carry it home.

Pharaoh ant

What to look for: much smaller, yellowish to light brown, sometimes almost translucent. Found indoors all year rather than seasonally, in heated buildings - around warm pipework, in wall voids and service runs, often in blocks of flats and other buildings with continuous heat.

What it tells you: that the standard approach is the wrong one. Chemical disturbance can cause a pharaoh ant colony to split and relocate into several new nests, so identification matters here in a way it does not with a garden ant.

What it rules out: if the ants are the familiar dark garden ant, active in summer, with a trail leading outside, this is not what you have.

Flying Ants

What to look for: winged ants emerging in numbers over a short period on a warm day, often across a whole neighbourhood at once. Larger females and smaller males.

What it tells you: mature nests nearby releasing new queens and males. That is all. It is not an infestation of the building they emerged beside, and it ends within days.

What it does not tell you: where the nest is with any precision, or whether it is on your property. Useful only as confirmation that a mature colony is somewhere close.

Trails to Something Sweet

What to look for: a two-way stream converging on a spillage, a fruit bowl, a bin, pet food or an open packet.

What it tells you: the food source, which is worth removing - not because it clears the colony, but because it stops the colony being rewarded while the treatment works.

Three Insects Mistaken for Ants

• Winged aphids and other small flying insects during a swarm - flying ants have a distinctly narrow waist and elbowed antennae, which most look-alikes do not.
• Small ground beetles. Hard-shelled and without the narrow waist, and they blunder rather than following a line.
• Springtails. Tiny, associated with damp, and they jump - which ants do not.

The narrow waist and the elbowed antennae are the two features worth learning. Between them they settle almost every ant-or-not question.

Photographing an Ant So It Can Be Identified

Mostly it does not matter which species you have. Where it does - a very small pale ant indoors all year in a heated block - a usable photograph is the difference between the right treatment and the wrong one.

1. Get one onto a plain pale surface. A sheet of paper, a white worktop, the back of an envelope. Anything patterned makes it much harder.
2. Put something next to it for scale. A matchstick, the tip of a pen, a coin.
3. Use good light and get as close as the camera will focus. Most phones will manage it; take several and keep the sharpest.
4. Photograph the side view if you can. The narrow waist is the most diagnostic feature there is and it does not show from directly above.
5. Include a picture of where they are running as well as the insect itself.

If you find a dead one, keep it in a clear bag rather than binning it. A specimen beats a photograph, and both beat a description over the phone.