There is none, but research has shown that spraying 1 pint of Castor Oil over 2,500 square feet every 6 to 8 weeks will deter the buggers.

To have success with a castor oil treatment, you need to first make an emulsion out of the product. To do this, blend 6 ounces of C.O. and 2 tbs. dish soap with one gallon of water. This becomes your concentrate. Mix 1 ounce of that per every gallon of water to apply to your lawn. A hose end sprayer is a good tool for this job, as it will allow you to put down a soaking application.

You can also purchase castor oil repellents for this very purpose.

The castor oil sprays are a very temporary fix for me, if they work at all.

I only wish the moles would favor my lawn - they could have the darned lawn that I can easily repair. Instead of sod, the lazy critters prefer my perennial and shrub beds for their tunneling and mounding. Lots of compost in the beds, but only organic products on my grass and nothing to deter grubs or worms, so go figure...

Would a harpoon trap be considered 'organic' or 'non-toxic'? ;-)

I bought two of the Mole Pro. Watched the video carefully. Either the moles watched it before I did, or I do not have moles with normal predictable behavior.

They are supposed to be easy to set (without losing fingers) and that's true, reliable when placed in that straight active run between mounds, easily distinguished from short feeding tunnels. OK, clear enough, but what about the zig zagging they do around shrub rootballs etc when I can't find straight runs at all. I've yet to trap a single mole :)

DH has eliminated three by standing very patiently and quietly with a foresters hoe in hand ....I'll leave the details to your imagination. I can tell you they love nightcrawlers but I won't tell you how I know.

Here is a link that might be useful: Mole Pro

I know a lot of people that for the last 40 years have been trapping moles every year, and they often trap 30 or 40 per year every year. To date there has not been a decrease in the population of the buggers from that trapping. As soon as you eliminate your mole from your yard another mole will move in to take advantage of that vacancy, unless something is done to make that vacancy unattractive.
Research at Michigan State University found that if a sufficient amount of Castor Oil was applied to make the food source distastefull the moles would go elsewhere, for a time. They, the research people at MSU, found that 1 pint of Castor Oil applied over 2,500 square feet was what was needed to accomplish that and the affect would last for 6 to 8 weeks before needing to be applied again. So if you mix 1 pint of Castor Oil in a 1 quart hose end sprayer with enough water to fill and spray that over the 2,500 square feet that area will be mole free for a time.

Kimmsr, climate can be a factor with repellent sprays and I should have pointed out mine is probably exceptional - with 85+ inches of diluting rain per year and ground that doesn't freeze. Moles are active all year round....

I know that you keep repeating the MSU study, Kimmsr, but there are plenty of other research based recipes out there. Mine is simply one (as is yours). I do think that making an emulsion with the soap is an important step in getting the product to penetrate the soil.

Killing moles as they forage is just one aspect of an integrated control program, and in some locations, an important one. Year round populations can be brought under control with persistence. The repellents are more likely to be helpful with few moles competing for the same food source.