Outdoor cat repellents come in a large range, in fact you have a choice of 3 main types: , , or . Ultrasonic are by far the most popular, simply because they are inexpensive, and they work for a long time. Water sprays can be equally as effective, but require a water supply, and are more expensive. Although powder cat repellents are the least effective and do not have the same staying power as an electronic device, they remain best sellers and are popular with gardeners looking for a quick inexpensive solution to cats that does not need batteries!
Boundary Indoor/Outdoor Dog & cat Spray Repellent.
I would also suggest the citrus peels. Oranges or grapefruits I think work just as well; do not use toxic things like mothballs, as that is even more horrible than outdoor cats. Are these cats bothering you or your cats or both? Are they spraying their scent around? If your cats are indoors all the time, you have a few more choices. I used a lemon scented Mr. Clean splashed over the places the stray cats were spraying, and that covered the smell and seemed to deter them. If your cats don't go outside, or you keep them in your yard, you might also try a cat repellant that you can buy in places like Walmart. There are different kinds. Might work.
Boundary Indoor / Outdoor Cat Repellent 14 Ounce Spray Can - Walmart
This spray is safe to use on your furniture and all other indoor and outdoor items and plants. This spray is great for training your cat or repelling the neighborhood cats.
Boundary Indoor / Outdoor Dog & Cat Repellent Aerosol Spray 14oz
Boundary Indoor/Outdoor Cat Repellent works as an effective training aid in and around the home to repel cats from areas they don't belong including furniture, carpet, trees, shrubs, garbage cans/bags, and other "forbidden" areas. Ready-to-use, aerosol spray formula applies in seconds and repels cats for up to 24 hours when applied daily. Repels cats away from forbidden areas.
Like all outdoor cat repellers the SSScat uses an ultrasonic detector to activate whenever it senses movement over a one meter radius. Once triggered the device sends out a blast of harmless spray, frightening the cat momentarily. There are no chemicals other than the propellant, it is purely the fright of the noise and spray that has the desired effect on the cat, or pet. Customers have reported that even once the spray is exhausted and in need of a refill, the cats still avoid the area, as they have associated the visual presence of the ssscat with the scare and refuse to go near it.