At first glance, mealybugs definitely don't look like your typical pest. Their 1/16- to 1/8-inch-long bodies are white, oval in shape, and covered with wax, which makes an infestation look more like cotton balls than bugs. Even with this relatively distinct appearance, they can be hard to spot since they gravitate toward the undersides of leaves, leaf axils, or protected areas at the base of certain plant varieties. Typically you'll find these pests in warmer climates, targeting citrus trees and ornamental plants such as orchids, gardenia, English ivy, fuchsia, coleus, and more, both indoors and outdoors but especially in greenhouses.
When they latch onto your greenery, mealybugs will suck out its sap (its primary food source) and harm the plant. While low numbers may not cause significant damage, large populations can slow plant growth, so you'll want to keep an eye out for signs. Mealybugs may cause existing leaves to turn yellow and new growth to fail, and they excrete wax and sticky honeydew, which is often accompanied by black, sooty mold-any of which are good indicators that the mealybug may be the culprit for failing plants, even when the bug itself may otherwise be hard to spot.
Once you've ID'ed the pests, it's time to try out some strategies for how to get rid of mealybugs.
Step 1: Removal
Chemical treatments typically aren't very effective because they are repelled by the mealybug's waxy coating. Try these methods as your first course of action.
• Manual removal of the bugs: Hand-pick mealybugs from infested plants if there aren't a prohibitive number of pests present. Use a drop of isopropyl alcohol on a cotton swab and dab it on the bug to remove it. Test the solution on a small part of the plant one to two days ahead of time to make sure it doesn't burn the leaf. Spray sturdy plants with forcible streams of water if mealybugs are present to knock large numbers of them off the plant.
• Introduction of natural enemies: Some predatory insects that prey on mealybugs can help control the mealybug population under controlled settings. The Cryptolaemus montrouzieri, known as the mealybug destroyer, is available commercially-if you can't find them available at your local garden center, they can be ordered online-to be released in greenhouses.
• Control of the ant population: Ants are known to protect mealybugs from natural enemies, so they can feed upon the honeydew produced by the mealybug. Use ant control techniques if you spot unusual numbers of ants on your plant.
• Removal of the infested plant: Finally, often the best course of action is to remove the source plant completely if it's heavily infested to minimize further spread. Once you've done that, inspect pots, tools, and other materials that may have come into contact with the plant for mealybugs and egg sacs; discard or clean any that show signs of infestation.
Where there is too large a population to use manual or biological methods, consider insecticides. Though they won't speedily wipe out your entire infestation, the young mealybugs will be affected of first, as they are particularly susceptible because they haven't yet developed their full waxy protective covering. Insecticidal soaps, horticultural oil, or neem oil insecticides may provide some suppression. Rotate methods each time you apply an insecticide to delay resistance; multiple applications will be needed throughout the season for best results. Make sure to apply these thoroughly to the undersides of the plant, since that is where mealybugs often hide.
Step 2: Prevention
Now that they're gone, make sure mealybugs never get in your garden again. Always inspect every new plant for mealybugs-remember: watch out for honeydew and black mold on leaves-before bringing them home. As you grow your garden with new plant purchases, you may also want to work with the garden center expert so as to stay away from plants known to be mealybug bait.