Mealybugs (Pseudococcidae) are a common plant pest that appears as cottony masses on stems and leaves. Soft-bodied and sap-sucking, these insects can be found feeding year-round in warmer climates. Mealybugs get their name from their white, powdery outer layer, which resembles cornmeal.
While harmless to humans, mealybugs can cause damage to houseplants by piercing plant tissues and depriving the plant of sap nutrients. In addition, mealybugs secrete honeydew when feeding, which encourages the growth of sooty molds on the infested plant.
These pests do not often cause significant damage to plants when in small numbers. However, larger infestations can lead to reduced growth and yellowed leaves. This may eventually result in plant death.
In this article, we’ll go over how to identify mealybugs and get rid of them.
Unlike spider mites and soil mites which are smaller than a grain of sand, mealybugs can be more easily spotted on plants. Adults are typically 1/10 – 1/4 inch long and appear as white, oval insects with clearly segmented bodies. Because they like to cluster together, these insects appear like cotton on plant surfaces.
They also like to gather in hard-to-reach nooks and crannies. An example of this is on the leaf axil, where the leaf meets the stem. For this reason, sometimes mealybugs go undetected until the plant is heavily infested.
Here are some common signs that you have a mealybug infection:
- White cotton masses in leaf axils or other sheltered places on the plant. Orange eggs might also be spotted in these locations.
- Black sooty mold is a sign of mealybugs. The honeydew secreted makes plants sticky and encourages the growth of black molds. This gives affected surfaces a blackened appearance.
- Loss of vigor in plants and premature dropping leaves is another sign of mealybugs. These insects pierce your plant’s stems and leaves, feeding on plant juices and depriving your plant of nutrients.
How to get rid of Mealybugs
Thankfully, there are several effective and cost-efficient ways to get rid of mealybugs.
However, before you use any treatment, there are two steps that you must take once you spot these insects.
- Firstly, remove the infected plant away from any other houseplants. This is because mealybugs can cross-infect other nearby plants. It’s also a good idea to spend some time looking closely at your other plants to check if they have been infested.
- Then, use sterilized garden shears to cut off dead or damaged leaves. It is easier to dispose of heavily infested parts than to try to eliminate mealybugs. Be careful to dispose of these securely as errant mealybugs or eggs may be hiding on leaf surfaces.
Now that you have isolated your plant and pruned it, it’s time to attack residual mealybugs!
These are three main options to treat your infected houseplants. We don’t recommend using synthetic chemicals as mealybugs are resistant to most of these. Synthetic chemicals can also be harmful to humans when exposed over extended periods.
Option 1: Insecticide Soap Spray:
Option 1 is our go-to solution: Bonide Insecticidal Soap. This broad-based insecticide and miticide use naturally occurring potassium fatty acids to kill pests.
Fatty acids penetrate an insect’s body covering and impact their cell membranes. Cell contents leak out, causing the insect to die.
Unlike synthetic chemicals, insecticidal soap does not persist in the environment. The latter is environmentally friendly and appropriate for organic gardening.
To use, shake the bottle and spray infected leaves and stems thoroughly. Be sure to check for the infestation at different angles of the plant, on the underside of leaves, and at leaf axils. These pesky bugs like to hide!!
Also, check the bottom of the pot as they may hide around the plant’s pot or saucer. For thoroughness, it’s good to clean the area your plant was located for any errant bugs.
Re-apply weekly or twice a week in severe cases until the infestation has passed.
Option 2: Isopropyl Alcohol and Dish Soap Spray:
If you prefer a homemade solution, this two-punch combination is a good one.
Separately and together, isopropyl alcohol (rubbing alcohol) and soap dissolve mealybugs’ waxy outer layer on contact. Without this protective covering, the insects soon become dehydrated and die.
Here’s how to create this alcohol and dish soap spray:
- Add 3 cups of 70% isopropyl alcohol into an empty spray bottle.
- Mix in 3 cups of water.
- Add one teaspoon of soap to the mixture.
- You can also add in 1 teaspoon of neem oil for added punch.
- Before using, shake the bottle to ensure the solution is emulsified.
Spot-test this spray on a small portion of the plant. Wait until 48 hours have passed with no adverse effects before applying thoroughly to plant stems and leaves.
Ideally, use this spray in the morning when evaporation is slower. This allows more time for the solution to work.
As above, the same principle of checking different angles of the plants, their pot, and under its saucer for pesky hiding bugs applies. You can use this same alcohol-soap spray to clean the area your infected plant was located.
Re-apply weekly until the infestation is gone.
Option 3: Neem Oil:
Neem oil is another good option to eliminate mealybugs. This naturally-occurring oil covers insects’ breathing holes. It also acts to smother eggs, stopping their maturation.
For details on using neem oil as an insecticide, check out our step-by-step guide here.
How to Prevent Mealybugs
Unfortunately for those living in the tropics, mealybugs prefer warm environments. They are also especially attracted to overwatered and over-fertilized plants.
While mealybugs crawl, they are unlikely to travel more than a few feet during their adult lives. For this reason, they are often introduced into a home by cross-infection. Usually, this takes the form of unknowingly bringing home an infected plant or contaminated soil from a nursery.
From there, mealybugs spread from plant to plant and increase in numbers as they feed off sap nutrients and reproduce.
Here are some tips to prevent mealybugs from attacking your beloved houseplants:
- Healthy plants are your best defense. Mealybugs, like many other pests, are attracted to stressed plants. Healthy plants are also more likely to withstand infestations. Ensure you provide your plant with the proper care – our plant guides are an excellent place to start.
- Thoroughly examine any new plants for potential pests before introducing these into your home. Regularly checking in on your plants for any new signs of infection is also good practice.
- Examine any potting soil before use. In the same way, cross-infection may occur through contaminated potting soil.
- Use proper watering techniques. Overwatering is a common struggle, and it doesn’t help that mealybugs are attracted to overwatered plants! Our guide on watering your plants properly can help.
- Ensure that you do not over-fertilize your plants. Generally, any liquid fertilizer needs to be diluted to half or quarter strength for most houseplants. Also, remember to reduce the frequency of fertilizing during the winter months, when growth is slow. Check out our plant guides for detailed instructions.
- You can use neem oil as a preventative spray for maintenance. Here’s how.
- After treating mealybugs, ensure you properly dispose of any infected or damaged leaves.
Mealybugs are a common houseplant pest that may be introduced into your home by an infected plant. Thankfully you can get rid of them by using insecticide soap spray or a homemade alcohol and soap solution. Neem oil is another effective way to kill these pests.
As always, prevention is better than cure. Regularly inspecting your houseplants for pests and ensuring you give them the proper care to grow healthy are two main ways to prevent infestations. Neem oil sprays can also be used preventatively as part of your plant care routine.
Frequently Asked Questions
Can mealybugs bite humans?
No, thankfully not. While they certainly can cause damage to your plants, they cannot harm humans.
What plants are most susceptible to mealybugs?
Unfortunately, tropical houseplants are amongst those susceptible to mealybugs. This is because mealybugs prefer warmer climates. Added to this, they do like plants with softer stems, such as Orchids.
Can plants recover from mealybugs?
Yes, they can if you act quickly enough using an insecticide soap, alcohol soap spray or neem oil. Most plants can withstand low infestation levels, giving you time to attack before the population grows and more damage is done.
Can mealybugs jump?
No, they cannot. They crawl across surfaces, and certain adult males can fly.
Deborah is a plant enthusiast and founder of Gardening Collective.