Scale insects look like raised scabs or bumps, between 1/16 to 1/8 of an inch in diameter, and can be white, black, brown, gray or tan. “Armored” scale hatches, crawls for a few days, then permanently stops as they lose their legs and develop a cover that gives them their characteristic appearance. “Soft” scale is a little larger, with smooth or cottony covers. They can move a little while longer before settling in one spot to feed for life.

Mealybugs and adelgids are ovular, reaching 1/4 to 3/16 of an inch long. They are clearly segmented and look like greasy or waxy, white cotton fluff. When disturbed, they can move slowly and are usually found near crevices in between stems and leaves. They secrete sticky honeydew that makes the leaves look shiny. Every 30 days, one mealybug can produce an egg sac containing up to 600 eggs.

All three of these pests pierce into plants and feed on their sap. This activity weakens the plant and creates discolored spots. They can also lead to streaking or scarring on leaves. Additionally, leaves may curl or turn yellow/bronze. This damage can lead to leaf drop and eventually kill the plant.

On annual vegetables, the loss of leaves could affect production. Trees heavily infested with armored scale may look water stressed and ultimately die. The excretion of honeydew can lead to the growth of sooty mold.

Inspecting your plants regularly is essential for early detection. The easiest way to successfully rid plants of pests is to catch them early.

On outdoor plants, a forceful spray of water can help reduce populations. For houseplants, isolating the infected plant will help prevent spread. In the case of mealybugs, simply wiping with rubbing alcohol can remove them—but it’s important to remember that rubbing alcohol cannot be used on all plants.

For larger infestations, coating leaves with a spray of equal parts water and dish-washing soap (not detergent) can smother pests. This technique can also be employed using neem oil or horticultural oil, or insecticidal soap.

Multiple applications, around every 10 days, will probably be necessary. Prune infested leaves, twigs, and branches—then remove them from your property. Introducing lacewings or ladybugs, natural predators of these pests, can help reduce populations.

In severe infestations, synthetic systemic insecticides can be invaluable. Regardless of method or product used, always follow the instructions and never spray when beneficial insects are present.

Weak, under-potted, and stressed plants are more likely to become infested with these pests. Keeping your plants properly watered, fertilized, and overall healthy is the best way to avoid attracting them.