Large Aphids on My Cactus

Wooly Aphids

• Wooly aphids, or mealybugs, overwinter as eggs and hatch in in the spring. Female wooly aphids can produce hundreds of offspring, so what may seem a moderate population of pests can skyrocket quickly. These pests use their mouth sucking parts to eat the sap or nutrients from cacti, according to the Cactus Museum. Other than the damage wooly aphids produce, you may see their waxy skins on plants. Also, these pests leave a sticky residue on plants called honeydew.

Damage

• Pests attack all areas of cactus plants. You may see parts of the cactus begin to shrivel and rot. Their damage leaves areas that are susceptible for contracting fungal diseases, according to the Cactus Museum. Cacti that have been heavily populated by wooly aphids or received severe damage begin to rot. In addition, ants love eating honeydew. It is not uncommon for gardeners to battle a wooly aphid and ant infestation at the same time.

Cultural Treatment

• Gardeners can remove moderate wooly aphid populations by spraying their cacti with a strong stream of water. Moreover, aphids can be removed with rubbing alcohol, according to the Cactus Museum. Dip a cotton swab with rubbing alcohol and touch only the top of wooly aphids without coming in contact with the cactus. The rubbing alcohol can dissolve its waxy coat and dehydrate or kill of the bug. If cultural methods do not reduce their population, you will have to provide chemical treatment.

Chemical Treatment

• Use a pesticide that contains either malathion and dimethoate, as suggested by the Cactus Museum. To ensure that you do not cause damage to your cactus, water the plant the day before using the pesticide. Apply the pesticide according to its directions. Repeat the pesticide until you see a reduction in their numbers. If spraying indoor cactus plants, take your plant outside before spraying. Leave your plant in a shady outdoor area until you get control of your wooly aphid population.