Then it was time for our program, brought to us by our own Mickey McGuire. He spoke about Insect Pests on Cacti and Succulents. He pointed out that no pesticides had been tested for use on "our plants" and that therefore caution should be used. He covered some information about general entomology and revealed that there is a Cactus Bug that is used in Australia to control rampant Opuntia. The most common pests on our plants are Aphids, Whiteflies, Scale, and Mealybugs. Scale and mealybugs are especially difficult to deal with since they are encased in a waxy covering--along with the hundreds of eggs! Attempts to control these insects includes picking them off thoroughly, controlling ants, insecticidal soap, and chemical or biological pesticides.

Pesticides should be used with caution and never used indoors. They may damage foliage, so test before using it all over. He pointed out that some chemical pesticides can even damage plastic pots! In general: Insecticidal Soaps are fairly safe, although they can burn foliage with repeated applications. Imidacloprid-based pesticide ("Merit") is a systemic root drench that is long lasting, but don’t use it in the house. Malathion is a contact insecticide which has been used for a long time, so some pests are resistant to it, It smells bad and is not good for scale and mealybugs. Dimethoate (Cygon) is for use in greenhouses, but has been banned in several states. It is toxic to humans and is not safe for home use. "Natural" pesticides are based on citrus oils and spices. They are not for use on plants but are very safe to use in the house for the control of house pests.

Fungus gnats are also problems, especially inside houses and greenhouses. The larvae feed on stuff in soil, but the adults can cause problems. You can target the larvae with Bti (Gnatrol), or use mosquito dunks which should be crushed and added to water. It takes about 2 weeks to control the gnats.

There are a few insects that are economically important: cochineal scale on prickly pears are used for a red/pink dye and cactus bees are important for pollination.

Then Mickey warned us of a new insect pest that is spreading throughout the southeast U.S. It is the Cactus Moth (Cactoblastis cactorum) which is native to South America and has been released in Australia and South Africa to control invasive opuntias. It is now spreading in the U.S. and will be a significant threat to our native Opuntia species. He showed us photos of the egg stick and the larvae, which are gregarious and form webs over entire pads. There are 52 species of Opuntia at risk. If you see any sign of this insect, let Mickey know!