IDENTIFICATION — Cochineal scale are small (up to 1/4-in.) crimson insects that attack Opuntia, such as prickly pear and cholla cactus. They’re easy to spot by the little tufts of white cotton that they produce to protect themselves from the sun, predator insects and birds.
DAMAGE — The insects suck the juices of the cactus and are found mostly in the lower elevations in the western United States and Mexico. The legless females can’t crawl — but the juvenile insects travel by hitching rides on the feet of birds. If left unchecked, cochineal scale can kill the plant.
CONTROL — When there are just a few insects, a sharp jet of water will knock them off the pads. For heavy infestations, spray the plants with malathion three times, at weekly intervals. That ensures that you get all of the newly emerging critters. You’ll know they’re dead when the cottony covers turn dingy gray or they no longer “bleed” red when you pinch them.