Scatter some mothballs in the attic, the shed, or under the hood, and the rats will stay away — it is one of the most common pieces of rodent advice passed around Tucson. It is also, unfortunately, mostly wrong. Here is the honest answer.
The short version
Mothballs do not reliably repel rats, and using them the way people do is both ineffective and, technically, misuse. Mothballs are a pesticide registered for one purpose — killing clothes moths in a sealed container — and using them scattered around an attic or engine bay is off-label. At the concentrations that build up in a sealed closet they work on moth larvae; scattered in open or ventilated space, they never reach a level that troubles a rat.
Why they seem to work at first
Here is the trap. When you first put mothballs down, the smell is strong and a rat may avoid the area for a few nights. That is just long enough for you to conclude they worked. Then the animal habituates to the smell — especially with food, water or shelter on the other side of it — and carries on. A hungry pack rat will not abandon a warm engine bay over a smell it has gotten used to.
The real problems with mothballs
- They off-gas naphthalene or paradichlorobenzene — chemicals you do not want vaporising in your attic, garage or car, especially around children and pets.
- They do nothing about entry points. Even in the best case they might move a rat a few feet; they never seal the gap it came through.
- They create a false sense of security while the population grows behind the smell.
What actually works instead
Rodent control in Tucson comes down to three things mothballs cannot do:
- Exclusion — sealing the roofline gaps, weep holes, door seals and penetrations rodents actually use. This is the foundation. See our exclusion service.
- Trapping — clearing the animals already inside, placed on their runways.
- Removing resources — middens, clutter, fallen fruit, accessible food.
None of that is as easy as tossing a box of mothballs in the attic, which is exactly why the myth persists. But it is the difference between a fix and a smell.
Other remedies in the same category
Peppermint oil, dryer sheets, and ultrasonic devices all share the mothball pattern — plausible, popular, and unreliable. See do ultrasonic repellers work for the evidence on the electronic version.
Quick answers
Will mothballs keep pack rats out of my car?
Not reliably. The engine bay is ventilated, the smell dissipates, and a pack rat habituates quickly. A light left on the engine works better, and fixing the yard staging habitat works best.
Are mothballs dangerous to use this way?
Using them scattered in open spaces is off-label and releases chemicals you do not want to breathe. It is a poor trade for a deterrent that does not hold.
Is there any home remedy that works?
Removing food, water and shelter genuinely helps, and sealing entry points works. Scent-based repellents do not reliably clear an established problem.
Skip the mothballs and fix the actual gaps. Book a free inspection and we will show you where the rodents are really getting in.
Not sure what you are dealing with?
A free inspection identifies the species, every entry point and the scope of work — in writing, before anyone quotes you a number.
