This one comes up constantly, and the answer is no on two counts. First, mothballs don't work — iguanas ignore them, and whatever faint effect they might have fades as the balls dissolve. Second, and more important, scattering mothballs in the yard, in burrows, or around a seawall is illegal. Mothballs are a registered pesticide labeled only for enclosed use against fabric pests, and using them outdoors is an off-label use that violates federal pesticide law.
Beyond being illegal and ineffective, they're genuinely dangerous. The active chemicals — naphthalene or paradichlorobenzene — leach into soil and groundwater and are toxic to pets, wildlife, and children who might find and swallow what looks like candy. In a South Florida yard, where water tables are high and rain is constant, scattering them outdoors is close to worst-case for where you'd want that chemical to go. We won't recommend them, and we'd steer any neighbor away from the idea.
Why the myth persists
The mothball idea spreads because it sounds plausible — strong smell, must repel animals — and because people share it online without ever confirming it worked. In practice iguanas are driven by food, warmth, and denning ground, not repelled by odor in any lasting way. A pungent smell doesn't override an animal's need to bask, eat, and shelter. The smell fades; the iguana stays.
What to do instead
The things that actually work aren't chemical shortcuts. Remove the resident animals, backfill their burrows so nothing moves back in, and put up physical barriers — tree wraps, piling guards, screen guards — where the animals have to pass. Those don't wash away, don't poison your yard, and don't put you crosswise with pesticide law.
Common questions
But I read online that mothballs keep iguanas away — is that wrong?
Yes. It's a persistent myth. They don't work, and the off-label outdoor use is illegal and toxic — not something we'd ever put in a client's yard. The people repeating it online almost never went back to check whether it actually worked.
Are mothballs really that dangerous outdoors?
Yes. The chemicals leach into soil and groundwater and are toxic to pets, wildlife, and children, who can mistake them for candy. In high-water-table South Florida, scattering them outside is close to the worst place you could put that chemical.
What should I use instead?
The things that actually work: removal, burrow backfill, and physical barriers like tree wraps and piling guards. No scattered chemical is a shortcut around those, and the ones people reach for are illegal, ineffective, and harmful.
