There are hundreds of insect species known collectively as mealybugs, nearly 300 of which are found in North America. They cause damage by sucking the juice from their host plants, especially from new growth, so luckily learning how to get rid of mealybugs and reduce or stop an infestation is possible.
What Are Mealybugs?
Mealybugs are small, oval sap-sucking insects related to scale insects. These warm-weather bugs measure 1/10 to 1/4 inch and secrete a powdery wax substance as a protective coating.
The mealybug's coating has a white cottony appearance, making them easy to identify when they appear on the stems and leaves of plants. In northern climates, they are principally a problem with houseplants and are found in private greenhouses but are rarely seen outdoors. In warmer climates, however, they can pose a serious problem for entire crops.
A light mealybug infestation can be easy to get rid of, but if it's a heavy infestation, you may need to toss the plant if it's indoors, and for outdoor plants with heavy infestations, repeated treatments are suggested. Over time, their damage causes the leaves to yellow and eventually drop from the plant. Mealybugs can also cause fruits, vegetables, and flower buds to prematurely drop off. In a bad infestation, their waxy excretions (also known as honeydew) encourage the development of sooty mold fungus.
Read on for seven methods that help you get rid of mealybugs outside and on houseplants.
7 Ways to Get Rid of Mealybugs on Plants
Method 1: Wash Mealybugs Away
Mealybugs can be dislodged with a steady stream of water. Repeat the treatment as necessary. This is best for light infestations, and some plants do not tolerate this kind of vigorous treatment.
Method 2: Use Isopropyl Alcohol
Soak a cotton ball with regular rubbing alcohol and wipe it on the mealybugs, which kills mealybugs instantly and removes them. Use a solution consisting of no more than 70% isopropyl alcohol, and test it on one leaf before you apply it to the whole plant to make sure the alcohol doesn't burn it.
Method 3: Spray With Insecticidal Soap
Insecticidal soaps are available on the market or you can make your own by using a mild dish detergent. Try to find a product free of perfumes and additives that might harm plants. Mix the soap in a weak concentration with water (starting with 1 teaspoon of dish soap per gallon of water and increasing as necessary). Spray the soapy solution on plants.
Method 4: Use Neem Oil
Use neem oil to get rid of mealybugs naturally. Neem oil's natural substance is derived from the neem tree. When used as directed, it affects an insect's feeding abilities, growth, and development, plus acts as a repellent. According to the Environmental Protection Agency, neem oil is safe to use on vegetables and other edible plants, as well as ornamentals.
Method 5: Introduce Predatory Insects
Lacebugs, parasitoid wasps (Leptomastix dactylopii), and a beetle sometimes known as the "mealybug destroyer" (Cryptolaemus montrouzieri), all naturally kill mealybugs. These natural predators are more commonly used for outdoor infestations or in greenhouse situations and are available from commercial online retailers.
Method 6: Use Homemade Insect Spray
To make a batch of homemade garden pesticide, combine 1 garlic bulb, 1 small onion, and 1 teaspoon of cayenne pepper in a food processor or blender and process into a paste. Mix into 1 quart of water and steep for 1 hour. Strain through a cheesecloth and add 1 tablespoon of liquid dish soap. Mix well. The mixture can be stored for up to 1 week in the refrigerator. Spray the solution on the plant parts where mealybugs are present.
Method 7: Use Synthetic Chemical Pesticide
Several stronger insecticides are approved for use against mealybugs, but the protection offered by the wax on the insects can make these pesticides less effective. Be cautious when using these chemicals, especially in indoor locations. Stronger pesticides have varying degrees of toxicity to humans.
Click Play to Learn How to Control a Mealybug Infestation
What Causes Mealybugs?
Mealybugs tend to be drawn to certain plants that are abundant with juices they prefer to feed on. Citrus trees are particularly susceptible, and mealybugs can pose a serious threat to some commercial crops, such as mango. Mealybugs can infest a number of indoor houseplants, particularly tropical species.
Mealybugs are attracted to plants with high nitrogen levels and soft growth; they may appear if you overwater and over-fertilize your plants.
How to Prevent Mealybugs
Like most pests, the best control for mealybugs is defensive. Healthy, vigorous plants are less susceptible to infestation than weak, underpotted, and stressed plants. As a general rule, make sure your plants are healthy, and you're less likely to attract these pests in the first place.
However, mealybugs can infect even healthy plants. Often, they come in on new plants, because greenhouses are the perfect breeding ground for them. Check any new plant purchases carefully before adding them to your collection.
Many other strategies can help prevent mealybug infestations on your plants:
- Reducing feeding and watering may sometimes prevent mealybugs since it reduces nitrogen levels and hardens a plant's growth.
- Wiping foliage regularly with a leaf shine solution containing neem oil may prevent mealybugs on susceptible plant species.
- With plants that can tolerate such treatment, regular spraying with hard blasts of water can prevent mealybug infestations from taking hold.
- For indoor plants that can tolerate it, dropping nighttime temperatures to 60 degrees Fahrenheit will discourage mealybugs, which prefer more tropical temperatures.
If an infestation cannot be controlled after two or three weekly applications of insecticide, consider destroying the plant before the mealybugs spread to other plants in your home.
Mealybugs vs. Scale
Mealybugs are closely related to scale insects, but mealybugs are soft-bodied, rather than wearing the hard protective shells found on scale insects. Rather than the fluffy, cottony material, scale insects create a hard, barnacle-like coating on the leaves and stems of plants. The methods for getting rid of scale are very much the same as for mealybugs.
How long do mealybugs live?
Female mealybugs lay from 300 to 600 eggs, which hatch in a few days. Within six to 10 weeks, the hatched insects are ready to lay eggs, so an infestation of mealybugs can perpetuate itself almost indefinitely unless they are eradicated.
Do mealybugs bite or sting?
Mealybugs do not pose any danger to humans; they feed only on the juices of plants.
What plants are most susceptible to mealybugs?
There are so many species of mealybugs that almost any indoor plant can be susceptible to these pests. In particular, tropical plants with softer stems and leaves are very likely to develop mealybugs. Orchids, African violets, begonia, coleus, and amaryllis are among the plants known to be especially susceptible, but in warmer climates, many outdoor plants are likely to experience infestations. Mealybugs thrive at temperatures between 70 and 90 degrees.
Mealybugs on Orchids. American Orchid Society.
Mealybugs. Missouri Botanical Garden.
Mealybugs. NC State Extension.
Mealybugs Management Guidelines. University of California Integrated Pest Management Program.
Neem Oil General Fact Sheet. National Pesticide Information Center, Oregon State University Extension Services.
Cold Pressed Neem Oil (025006) Fact Sheet. U.S. Environmental Protection Agency.
Citrus Mealybug. University of Florida IFAS.
Human Health Issues Related To Pesticides. U.S. Environmental Protection Agency.
Pest Alert: Pink Hibiscus Mealybug, Maconellicoccus Hirsutus (Green). Florida Department of Agriculture and Consumer Services, Division of Plant Industry.