Landscapes and gardens with opuntias (prickly pear and chollas) are occasionally confronted with a messy, potentially debilitating pest that looks like white cotton candy. This innocuous looking tuft of white is actually the home of the cochineal scale insect. If left untreated the cochineal multiplies and covers the plant. This is not only an eyesore, it can weaken and kill the host plant as the insect is sucking the plant juices.
How can you tell if you have cochineal?
REALLY SIMPLE, squeeze a small tuft of the white stuff. If you have a cochineal infestation, the tuft will turn a crimson red. The cochineal insect was the source of red dyes for fabric!
How do I get rid of cochineal?
If you catch the problem in the very early stages with just a few white tufts, you can spray them off with water. Be sure to do a thorough job and check back every few days. Repeat as necessary.
If the problem is more advanced, you probably will have to use chemicals. We find Malathion to be adequate. Mix to the recommended strength for ornamentals — cactus is usually not listed on the label. Add a little liquid soap to the mix so the water/Malathion stays on the plant better. Spray thoroughly paying special attention to the places where the pads or joints come together. This process should be repeated seven days later and again fourteen days later to catch the bugs you missed AND to get the newly hatched cochineal that were protected by egg cases. You will know your treatment is successful when the white tufts turn a dingy gray and squeezing them does not produce the crimson stain.
How does cochineal spread?
Cochineal is spread by sticking to bird’s feet so you have to maintain your vigilance! Catching it early enough to be treated with water only is far preferable to chemicals. They are especially attracted to purple prickly pear and Christmas cholla cactus!