Organic Mealybug Control Indoors and Out
Use Natural Pesticides to Kill Flower Garden Pests
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They may look like little fluffy cotton balls with legs, but the damage mealybugs can do on houseplants and in the outdoor garden is serious. Mealybugs, a cousin to other garden pests like scale and whiteflies, can damage many flowering and ornamental plants by direct feeding and by introducing diseases into the garden. Organic gardeners can control this pest in several ways without resorting to toxic pesticides.
Identify Mealybugs and Mealybug Damage
Mealybugs are tiny insects, about 1/8 inch in length, but their color and clustering habit make mealybugs easy to find on garden plants. Most common mealybug species are white and have waxy looking filaments covering their bodies, giving them a fuzzy or hairy appearance. An exception is the hibiscus mealybug, which is pinkish-brown and lacks the fringe.
What plants to mealybugs like to feed on? Many of our favorite houseplants are susceptible to mealybug infestations, including gardenias, jade plants, ficus trees, English ivy, hoya, and palms. In the outdoor garden, watch for mealybugs on coleus, begonias, Gerbera daisies, marigolds, and chrysanthemums. Any plant that has experienced high nitrogen levels from over-fertilization will be especially appealing to the pests.
Mealybugs feed on garden plants by inserting their sharp mouthparts into the leaves and stems to suck sap. Damaged leaves look wrinkled or puckered, and the insects can contaminate cut flowers with webby egg sacs and clusters of larvae. The honeydew mealybugs excrete compounds the damage, as it harbors black sooty mold and encourages the growth of plant viruses.
Deal With Small Mealybug Outbreaks
You can manage small mealybug infestations with a simple blast of water. Use a plain jet of water to disrupt the bugs’ feeding, and spray plants with neem oil to discourage the bugs from coming back. Neem oil spray will not affect bees, making it ideal for the pollinator-friendly landscape.
Integrated Pest Management for Mealybugs
Several species of parasitic wasps prey on mealybugs, so flower gardeners should attract these predators with nectar-rich plantings of yarrow, sweet alyssum, and bee balm. Lacewings and pirate bugs also feed on mealybugs, so gardeners should be aware of the possibility of damaging these pests with insect spray, even if the spray is organic.
The honeydew mealybugs exude attracts ants, which aren’t pests themselves, but protect mealybugs from natural predators. Planting common vetch as a cover crop can draw ants away from mealybugs by providing a supplemental nectar source. Gardeners can also discourage ant colonies by tilling the surface of the soil to disrupt nests.
Biological Pest Control for Mealybugs
Organic gardeners have at least two commercial options for biological mealybug control. The ladybug species Cryptolaemus montrouzieri, commonly called the mealybug destroyer, feeds voraciously on mealybugs at all stages of development. In fact, gardeners must take care not to mistake this beneficial insect for a pest, as the larvae of this ladybug resemble mealybugs. Gardeners can order adult mealybug destroyers to release during periods of high infestation, and this ladybug will feed on other garden pests like aphids or thrips when the mealybugs are gone.
Gardeners can use the OMRI (Organic Materials Review Institute) approved insect-killing fungus marketed under the trade name Mycotrol, which contains spores of Beauveria bassiana. Gardeners can use this product until the day of harvest for cut flowers, as it’s safe for people, animals, and the environment.
Organic Sprays for Mealybugs
As soft-bodied insect pests, mealybugs are susceptible to insect soap sprays. Gardeners must spray mealybugs directly with the insect soap to disrupt the cell membrane and kill the insects, so this spray doesn’t work as a preventative agent. Insect soap is a short-acting spray, and you must reapply weekly for as long as the pests are active.
The biggest drawback of insect soaps is their potential to damage or burn plants. To reduce plant toxicity, spray plants in the evening and spray them with water in the morning, as high temperatures and sunlight increase plant damage from insect soap.
Mealybugs on Houseplants
Mealybugs and their nymphs thrive in greenhouses, making this insect pest common on houseplants. Orchids are particularly susceptible to damage and death from mealybug infestations. Isolate new houseplants for one week before placing them around other houseplants. Inspect the plants each day for signs of white mealybugs or their webbing, and kill any insects with a cotton swab dipped in rubbing alcohol.
Don't let their cute fuzzy appearance fool you, mealybugs damage many garden plants in the landscape. Here's how to control them organically.
How To: Get Rid of Mealybugs
Though sometimes hard to spot, mealybugs often leave behind telltale signs of their presence. Follow this guide to rid your garden of these waxy pests for good.
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.
Once you’ve identified the cottony-white pests on your failing plants, try out some these top strategies for how to get rid of mealybugs.