Ants climb walls using a combination of three features: claws, suction pads, and grippy hairs on their feet. They will apply one, two, or all of these biological capabilities to climb just about any surface.
Generally, ants will be able to climb just about any surface, including glass. There is a small number of very smooth man-made surfaces that ants cannot climb, such as Teflon, which can be used in ant enclosures to prevent them from escaping.
Amazing, the ant’s incredible wall climbing skills has been inspiration for wall climbing robots such as Stanford University’s SpinyBot II and the American Institute of Physic’s ZPD robot.
The 3 Ways Ants Climb Walls
Ants don’t just have one trick up their sleeve when climbing walls. They actually have three! These are: suction caps called “pretarsal adhesive pads” or arolia, claws for grip, and tiny hairs for traction.
1. Pretarsal Adhesive Pads (Causing Capilary Adhesion)
The primary mechanism for achieving grip on walls and ceilings is the “pretarsal adhesive pad’ on the feet of ants. These pads are sticky.
When the ant applies pressure to the wall, the wet sticky substance inside the pad seeps out and fills in all the little gaps of air between its feet and the wall.
The effect is that the ant doesn’t just hold the wall, it actually sticks to the wall. The physical process that’s occurring is called “Capillary Adhesion”.
In school, we can replicate capillary adhesion by pouring water onto a glass surface. Then, place a flat-bottomed mug (a beaker works great) on the small puddle of water and press down. You’ll feel the beaker sticking to the surface!
What’s happening is the surface tension of the water is causing the surface and the ant foot (or in our experiment, the beaker), to stick!
You can see the scientist in this video doing that experiment:
2. Claws for Grip
On rough surfaces, ants can use special claws on the back of each foot to grip onto the surface.
The ants’ claws are really quite big relative to their size. So, they can get a good sharp grip on surfaces. They sit at the back of the front foot facing forward.
It’s a bit like an ice climber with his big pick. He’ll hammer that pick into and around rocks and ice to get a grip as he climbs the frozen waterfall.
But the claws can serve another purpose, too.
An ant’s claws can be used to help unpeel that adhesive pad from the wall. Every step, that pad needs to come unstuck so the ant can move his foot forward as he climbs (and yep, all worker ants are male!)
3. Hairs on Feet
Ants use the hairs on their feet to hold on, but the suction caps do most of the work.
Usually, as the ant climbs, it will use suction caps to hold on, then the hairs as a back-up to hold them there, almost like a hand-break.
Other types of insects like ants use the thousands of tiny hairs on their feet to grip into even the tiniest gaps in walls. For those insects, they use what we call “hairy pads” because they have so many more hairs. But ants have smooth pads with hair as a backup grip only.
How to Stop Ants from Climbing Walls
There are several ways to stop ants from climbing walls. You can either buy a slippery adhesive to put on a glass surface, or you can simply use insect surface sprays regularly.
For people who keep ants in ant farms (for a hobby, or for science experiments), you are going to want to get a slippery adhesive. This will prevent the ants from climbing out of their cage without causing them any harm.
Two common adhesives are Fluon and PTFE products. They’re very low-grip adhesives that cause ants and similar insects to slip and fall. You can buy either liquid product that you can add using a sort brush and allow to dry, or strips that you apply like tape.
For the slippery liquid, you’re looking at 16 oz for $99. Here’s footage of it in use on an ant farm:
For people seeking a pest control solution, you can use store-bought insect repellant sprays.
Choose an ant repelling surface spray that stays on surfaces for a long time. Spray a line of the repellant along the base of the wall and, if you can, at the top as well.
Remember that these sprays may need to be re-applied regularly, especially if the area is exposed to the elements (such as rain).
Make sure you read the label and follow the instructions carefully. Some repellants may irritate children or pets. See the label of your spray for more information.
Do Ants Die from Falling?
It’s possible that ants may die from falling, but it’s likely they’re too small and light to achieve enough velocity to ‘splat’ on the ground. Air resistance against their tiny bodies will slow them down.
Furthermore, their exoskeleton will help to protect them from a hard fall.
This isn’t a hard thing to try out. Just pick up an ant and drop it! You’ll see that it simply rolls over and runs away.
Common Ant Species That can walk on Walls
The following are some of the most common ant species found in interior walls and voids:
Odorous Ants: They build their nests in wet spaces such as wall voids near pipes, bath traps, and termite-damaged wood and feed on proteins and starches.
Argentine Ants: Argentine ants build their nests in wall cavities, bath traps, and insulation and feed on carbohydrates, sugars, and fats.
Acrobat ants: Acrobat ants build their nests in the window and door frames, especially those damaged by termites, other insects, or wetness; they eat sugars and proteins.
Carpenter Ants: Carpenter ants build their nests on rotten wood that other insects have damaged.
Ghost Ants: Ghost ants build their nests under baseboards, inside potted plants, and in spaces between cupboards and firewood brought indoors; they forage for sweets and oil in the kitchen.
Crazy Ants: Crazy ants tend to feed on fats, sweets, grease and oils, found in carpets, wall gaps, and potted plants.
Pharaoh Ants: Pharaoh ants build their nests in moist areas like kitchens and bathrooms near water sources, inner wall voids, beneath floors, under baseboards, and window sills, and feed on proteins and sugars.
Indoor Ants: Indoors, tiny black ants may build nests in voids in walls, cabinets, and brick or stone veneer.
Citronella Ants: Citronella ants are winged ants that swarm indoors from cracks and crevices in floors and walls, as well as the basement and foundation: they feed on honeydew from aphids and mealy bugs living underground.
Applications in Robots
In recent decades, studies of how insects walk on walls and ceilings have led to technological advances.
One example is Spinybot II from Stanford University. Spinybot used lots of tiny spiky hairs, replicated from hairy adhesion pads of cockroaches, to create a wall-climbing robot that has applications in military and police operations.
Another is the American Institute of Physic’s ZPD robot uses vacuum suction feet that is modeled off insect feet.
Ants climb walls thanks to their liquid-producing pads that act like suction caps. When the liquid is excreted they get extra sticky. They use their claws to grip walls and detach their suction caps. Furthermore, Hairs on their feet and ankles help to sustain grip.
With a combination of these three biological capabilities, ants can walk on walls and ceilings. They can walk on glass, plastic, metal, and nearly every other surface. To prevent them from climbing, you either need to use a PTFE substance of spray the wall with an insect repellant surface spray.