Why Mole Sprays and Castor Oil Repellents Do Not Work

Castor oil products can push a mole off one part of a yard for a while. They cannot remove it, and that difference is the whole ballgame.

What these products actually do

Almost every mole repellent on a Georgia shelf is castor oil in some form — granules you spread, or a concentrate you spray through a hose-end applicator. The theory is that it makes the soil and the worms in it taste unpleasant enough that the mole moves on.

There is some real basis for this. Castor oil does appear to have a genuine repellent effect in some conditions. That is exactly why these products keep selling: people apply them, the ridges stop appearing in the treated strip, and it looks like it worked.

Moved is not gone

Here is what actually happened. The mole has a tunnel system that may run well over an acre. You treated part of your lawn. The animal shifted its feeding to an untreated section — often the back yard, a bed line, or straight over to a neighbour.

Nothing was removed. The population did not drop by one. You bought a temporary reroute, and the moment the product breaks down the animal walks straight back into the runs it never filled in.

Georgia rain is the other half of the problem

These products wash out. North Georgia gets serious rainfall, and our clay soils shed a lot of what lands on them. A treatment that needed to reach a working depth in the soil profile does not survive many storms at effective concentration.

That is why the label tells you to reapply, often monthly through the active season. Run those numbers across a full year on a decent-sized lawn and compare them honestly against a one-time trapping job.

The question to ask before you buy

Does this product remove the animal, or does it move it?

If the answer is that it moves it, then you are renting a result that expires, on a schedule set by the weather. Every reapplication is a payment on a problem that is still living under your grass.

Next: Poison Worms and Mole Baits: Why Results Are So Inconsistent →