The insect pests you’ll most likely see on your cactus and succulents are red spiders, thrips, scales, and mealy bugs. The latter two are easily brushed off with a small brush, but if the stems are frequently treated with clear water, soap suds, or a solution of fir tree oil, these pests will not cause serious trouble.

The red spider will never appear if watering is frequent. Fir tree oil helps to prevents thrips. Try other natural pesticides for your succulents and cactus. Read this guide to organic pesticides for more information.

Be aware that insecticidal soaps will damage some species of cactus and succulents permanently. Insecticides designed for roses often work well for cactuses as well.

Pests can open the way up for fungal diseases so it’s best to treat them as soon as possible. Many pests will die off if you treat the plant with rubbing alcohol as well.

Ron Smith, a Horticulturist with the NDSU Extension Service has an excellent troubleshooting guide to cactus on his website.