Ants on the desk, computer desk and dining table: why they come and how to keep them off

Ants on the desk usually come for food left out on it, such as a sweetened coffee, an opened bag of snacks, crumbs in the keyboard and a bin under the desk, combined with an easy way up, such as a desk pushed against the wall or window ledge, or cables hanging from the desk to the floor. The fix is to clear the food, follow the ant line to where it comes in, wipe the desk and its legs with water and a little dish soap, then cut the routes up the legs and cables. On a computer desk with electronics, never spray the desk or the devices.

This article is part of our series on ants in different spots around the home. It covers home desks, computer desks, dining tables and office desks. If ants are in several places at home and you do not know where they come from, read the overview in ants in the house first, then deal with each table.

Ants get on the desk because there is food they can find and a way for them to climb up. The things that draw ants most often are a coffee or milk tea left unfinished, sugar and creamer sachets, a snack bag simply folded shut, bread crumbs in the keyboard, and a bin under the desk holding fruit peel or food boxes. These give off sweet or greasy smells that foraging ants pick up easily.

The way up is usually something that has always been there, so nobody notices it: a desk edge against the wall or window ledge, charging cables and a power strip lead hanging to the floor, a file rack or pot plant standing against the desk, or a chair back touching the desk edge. Ants walking along the floor-wall joint find these bridges before they find the legs.

Causes people forget are the invisible ones: a sweet drink spilled and not fully wiped, leaving a sticky patch under the mouse mat, snack residue from hands on the wrist rest, and an open hand cream or lip balm. They are not food, but they hold enough sugar or oil to interest ants.

Yes, because there are electrical devices on it. Never spray ant spray, pour water or sprinkle powder on the desk or near the devices, as liquids and powders get into vents, keyboard gaps and ports. Switch devices off and move whatever needs moving before cleaning, then wipe the desk with a cloth dipped in water with dish soap and wrung out until just damp.

A desktop keyboard collects more crumbs than anything else. Unplug it or switch it off, turn it over and tap gently to shake crumbs out, brush between the keys with a soft brush and wipe the surface with a damp cloth as the maker recommends. If ants have got inside a laptop or the keyboard itself, read the more detailed steps in ants in a laptop.

Under a computer desk there is often a heap of power strips, adapters and cables that is warm and dark enough for ants to pass through or hide in. If you see ants going in and out of a power strip or wall socket, do not open it or spray anything in. Stop using that point and have an electrician check it; see ants in power outlets for details.

Start by taking all food and drinks off the desk, but do not wipe the ant line away straight away. First see where the ants come from. The line usually climbs the desk leg, the wall or a cable. In the evening, shine a torch down the line to the floor and follow it until you find the crack, skirting gap or window frame they come in through. That is the spot that really needs dealing with.

Once you know the route, wipe the whole line from the entry point to the desk top with a cloth dipped in water with a little dish soap, to remove the scent ants leave to guide others. Wipe the top, the underside of the edge, the legs and the floor around them. If you only wipe the top, a new group will follow the old trail back up within hours.

Then empty the bin under the desk, wash it if it is stained and switch to a bin with a lid. Open the drawers to check for forgotten snacks or sweets. Finally put things back one at a time, wiping the bottoms of cups and boxes dry first, because a sweet ring under a cup is what brings ants back most often.

A dining table gets more ants than a desk because it has food every day. What works is wiping the table straight after every meal, not just before bed, taking dishes to the sink immediately, and not leaving leftovers under a food cover on the table overnight. If food must wait, put it in a sealed box or in the fridge. A mesh food cover keeps flies off, but not ants.

Fish sauce, soy sauce, sugar pots and honey bottles that live on the table often have a sticky ring at the base and around the cap. Gather them on one tray, wipe the bottoms regularly and set the tray on an anti-ant pad with a 5 cm margin all round. The tablecloth should be short enough not to touch the floor, because a hanging cloth is a bridge that lets ants skip the legs.

If ants still climb the legs, wipe them dry and apply anti-ant gel in a full ring around every leg, or stand the legs in cups of water for a while as you look for the way in. If one side of the table is against a wall, move it out a little, or ants will simply climb the wall instead.

Keep as little food at the desk as possible, and only in containers ants cannot get into. A folded or clipped snack bag does not keep ants out, because small ants squeeze through the fold. Tip snacks into a plastic box or jar with a rubber seal round the lid and clip it shut every time. Keep sugar sachets, instant coffee and sweets together in one box rather than scattered around the desk.

Coffee or tea you drink during the day should have a lid, and the cup should be washed as soon as it is empty. Do not leave a cup with dregs overnight. If a regular cup lives on the desk, use a wipe-clean coaster and wipe it daily. A lunch plate eaten at the screen should go to the sink as soon as you finish, and the spot where it sat should be wiped.

A desk drawer with snacks is a favourite for ants because it is dark and nobody checks it daily. If you must keep snacks there, use a clip-lid box and check weekly for crumbs or torn packets. Snacks that ants have got into should go in a tied bag in a bin outside the room, not in the bin under the desk.

Yes, and it is the route people overlook most. Charging cables, monitor leads and power strip cords hanging from the desk to a heap on the floor act like ropes that let ants reach the desk without touching the legs. Even with gel around every leg, ants can still come up the cables. Tidying cables is part of keeping ants off the desk.

Use cable ties or a tray under the desk to bundle cables off the floor, so they come down to the floor at just one point where they plug into the wall. Fix the power strip under the desk or put it on a shelf that does not touch the wall, instead of on the floor in the corner. Then you know how many ways up the ants have left, and can block them all.

Never put gel or wrap anything on the plug, socket or charger. If you want to block a cable route, move or lift the cable instead. If ants are already inside a power strip, stop using it, do not tap or open it yourself, and ask an electrician whether it should be replaced.

An anti-ant pad goes under the things ants like on the desk, while gel is applied as a barrier line around the legs. They work in different places. On a desk, gather the coffee cup, snack box and sugar pot in one corner and set them on an anti-ant pad, leaving a 5 cm margin around every item. Even if ants reach the desk, they cannot get to what is on the pad.

The 30x42 cm anti-ant pad costs ฿148 and has about 20x32 cm of usable space after the margin, enough for a coffee cup, a snack box and a water bottle. It has no smell and needs nothing added. Before first use, rinse it with plain water and wipe it dry. If coffee spills on it, wipe it straight away, because dried residue on the surface stops the pad working fully.

KAI67 anti-ant gel costs ฿109 and is applied as a complete ring around each desk leg on a fully dry surface. Check the line now and then, as feet and mops wear it thin. We have not yet received the ingredient documents from the distributor, so if you have small children or pets that lick table legs, ask us on LINE before use. Compare other methods in how to keep ants away.

At the office you can only fix your own part: keep snacks in clip-lid boxes, wash your cup daily, wipe the desk before you leave and do not throw food scraps in the bin under your desk. The source is usually outside your desk, such as the pantry, a store room or a wall shared with the building kitchen, and that needs building management or the cleaning team.

If ants are on several desks at once, report it to building management with where you saw the line, when, and which way the ants were walking. Details like these help the building team or pest control find the source faster. Do not bring your own spray or chemical powder into the office, as colleagues may react to the smell or substance and it may break building rules.

The pantry is shared by everyone. If you can, agree to keep sugar, creamer and shared snacks in clip-lid boxes on an anti-ant pad, wipe the counter every evening and empty the food waste bin daily, not leaving it over a weekend.

Ants on the desk come back because the source is still there. Wiping removes only the scent trail and the ants on the desk at that moment, but a nest in the wall, under tiles, in a window frame or in a pot plant in the room sends out new foragers every day. If even a little sweet residue remains, the new group finds it and sets a new trail very quickly.

Spend two or three days watching when ants come up, which way they come and what they head for. If they come from a pot plant, move it off the desk or out of the room. If they come from a crack in the wall or the window frame, wipe that line and fill the gap with a sealant that suits the surface. With an old wooden desk that has grooves or hollows, check whether ants are nesting in the desk itself.

If you find the source but cannot reach it, for example inside the wall or under the floor, ant bait placed along the trail on the floor away from the desk can reduce ants at the nest. Use it exactly as the label says and keep it out of reach of children and pets, and never put bait on a table where food goes. For biting ants or ants in many places, contact a licensed pest control company.