Skip to content
Grow In Backyard
Squirrels & Wildlife

Why Do Squirrels Chew Wires? Teeth That Never Stop Growing

Squirrel incisors grow continuously and must be worn down. Why cable is the right shape and hardness for the job, and how to protect wiring properly.

By Zakaria 3 min read Save to Pinterest — opens Pinterest in a new tab
A red squirrel on a branch gnawing a stripped conifer cone held in both front paws
Photo: David Selbert, Pexels License, via Pexels
On this page

Because their teeth never stop growing. Squirrel incisors grow continuously and have to be worn down, and a cable is the right shape and hardness for the job. Almost none of it is swallowed.

The reason is dental

Rodent incisors are open-rooted: they keep growing for the animal’s whole life. Left unworn they overgrow, and an overgrown incisor stops the animal feeding.

So gnawing hard objects is not a behavioural quirk. It is maintenance the squirrel cannot skip.

What makes cable attractive is mechanical, not nutritional:

  • Roughly twig-sized — the diameter its jaws are built around
  • Good purchase — it can get a grip without the thing sliding away
  • The right resistance — hard enough to grind the teeth, soft enough to bite

This is why it also chews things with no food value at all

Plastic fascia, soffit board, irrigation line, garden furniture, deck rails, hose.

None of it is food. All of it is the right hardness. Once you see the behaviour as tooth wear rather than appetite, the pattern of damage in a garden stops looking random.

The roof is a different problem

In a loft or a soffit, chewing is doing two extra jobs:

  • Access. Getting through whatever stands between the squirrel and a cavity it wants
  • Nest material. Soft stripped material is useful

Which is why damage in a roof space tends to be worse than damage to an outdoor cable. The squirrel has a reason to keep going.

Gnawed wiring in a loft is a fire risk, not a cosmetic one

Stripped insulation exposes live conductors inside a space full of dry material, and rodent damage to wiring is a recognised cause of structure fires.

Have it inspected by an electrician. The section you can see is rarely all of it, and taping over the visible part leaves the rest undiscovered.

Cars

A parked car offers a warm, sheltered engine bay with plenty of cable at exactly gnawing height. That alone explains it.

The widely repeated claim that soy-based insulation in modern vehicles actively attracts rodents has been the subject of litigation and a great deal of coverage, but the evidence is contested — and squirrels were chewing car wiring long before those materials appeared.

It makes no difference to the fix.

What to do

Protecting cable from squirrels
Works?Notes
Metal conduitYesThe proper answer for a run you can reach
Steel split loom / spiral wrapYesFlexible; good for engine bays and awkward runs
Steel mesh over entry pointsYesThe actual fix for a roof
Capsaicin tape or pastePartlyPain receptors, not smell — needs renewing
Plastic split loomNoSame hardness as the problem
Scent repellentNoHabituates within days
Ultrasonic deviceNo evidence—

For a roof, exclusion is the only durable answer

  • Seal every gap with steel mesh or metal flashing — soffits, vents, fascia joints, gable ends
  • Cut branches back so nothing overhangs within about six feet of the roofline
  • Check it is empty first, and mind the breeding seasons — sealing an animal in is worse than leaving it out

Protecting the cable treats the symptom. Closing the route treats the cause.

Common questions

Why do squirrels chew wires?

Because their incisors grow continuously and have to be worn down, and cable happens to be the right shape and hardness for the job. A squirrel gnaws on hard objects throughout its life as basic maintenance, not out of hunger or spite. A cable is roughly twig-sized, gives good purchase, and offers just enough resistance to grind the teeth — which is also why they chew plastic trim, fascia boards and irrigation line.

Are squirrels eating the wire insulation?

No. Almost none of it is swallowed. This is tooth maintenance and, in a roof space, sometimes nest-material gathering and access work — chewing through whatever stands between the squirrel and a cavity it wants. Treating it as a feeding problem leads people to the wrong fixes, which is why bait and repellents do so little about it.

Is squirrel damage to house wiring a fire risk?

Yes, and it is the reason this is worth acting on rather than tolerating. Gnawed insulation exposes conductors inside a roof space full of dry material, and rodent damage to wiring is a recognised cause of structure fires. Damage found in a loft should be inspected by an electrician rather than taped over, because the section you can see is rarely all of it.

Why do squirrels chew car wiring?

A parked car offers a warm, sheltered engine bay with plenty of cable at gnawing height, which is enough on its own. Claims that soy-based insulation in modern vehicles actively attracts rodents have circulated widely and been the subject of litigation, but the evidence is contested and the behaviour long predates those materials. Either way the practical fixes are the same.

How do you stop squirrels chewing cables?

Put something between the teeth and the cable. Metal conduit, steel split loom or spiral wrap works where plastic does not; capsaicin-based tape or paste adds a deterrent that does not habituate the way a smell does, though it needs renewing. In a roof the real fix is exclusion — seal the entry points with steel mesh or metal flashing and cut branches back from the roofline.

Will repellents or ultrasonic devices stop it?

Not reliably. Scent repellents fade within days as the squirrel learns the smell means nothing, and ultrasonic devices have no good evidence behind them. Capsaicin is the exception worth trying because it acts on pain receptors rather than on smell, but it is a supplement to a physical barrier rather than a replacement for one.

Backyard Weekly

Know what to plant, week by week

Join the weekly email for seasonal jobs, fixes for what is going wrong, and gear worth buying.

Not ready to subscribe? The planting calendar is free and needs no email.

By subscribing you agree to our privacy policy. Grow In Backyard will never sell your address.

Keep reading