Have you ever looked at your plants and noticed white, almost powdery, 1/10 to ¼” inch long oval spots on the undersides of leaves or along the stems? Those little white spots are mealybugs – one of the most common household plant pests.
Of course, mealybugs also exist outdoors, and there seems to be very little talk on how to treat outdoor infestations. With that in mind, let’s look at how to get rid of mealybugs outside and make your space mealybug-free.
What You Need to Know About Mealybugs
Mealybugs are a type of unarmored scale hailing from the Pseudococcidae family, and approximately 275 species are known to exist in the US alone.
They pierce your plants and drink the sap, producing honeydew that often attracts ants.
While only one or two won’t do much damage to your plant in their lifetime, a colony can become devastating.
Depending on the mealybug species, a female ladybug can lay 50 to 100 eggs in her lifetime or give live birth. This can lead to a population in only a short period.
Unlike some scale species, mealybugs can move around, and their waxy coating is more powdery.
The wax still protects them against some pesticides, which leads to many of the stories you’ve heard that mealybugs are hard to kill.
However, many options exist to get them out of your garden permanently and employing more than one can increase efficiency overall.
How To Get Rid Of Mealybugs Outside?
Despite how difficult it might seem, mealybugs aren’t too difficult to get rid of, although you may need to employ more than one technique.
In fact, what makes mealybugs seem so tough to destroy comes down to their biology.
By Hand
You’ll want to do this early in an infestation (so you aren’t spending all of your time on the effort).
Simply push them from the plant with your fingers or a pair of tweezers and plop them into a bucket of soapy water.
If the waxy coating makes it a bit hard to get them off of more delicate foliage, you can dip a cotton swab in isopropyl alcohol and dab the mealybugs with it.
This will dissolve the wax coating, making it easier to remove them.
Insecticidal Soap
Many chemical pesticides cannot penetrate the mealybugs’ waxy coating, but some products, such as insecticidal soap, remain effective.
Insecticidal soap can be mixed with water and sprayed onto the plant, killing any mealybug it comes into contact with.
However, you’ll need to use multiple applications as this product works best on nymphs.
Also, you may occasionally switch products to prevent the mealybugs from developing resistance to any one product.
Natural Predators
There are several natural predators out there that love feasting on mealybugs.
By far, the most effective is the mealybug destroyer (Cryptolaemus montrouzieri), which can be purchased easily and will devour entire colonies over time.
Other popular mealybug predators include:
- Lacewings
- Parasitic wasps
- Predaceous midges
- Spiders
However, if you plan to hire help, you must tackle another potential problem: ants.
Many ant species have “domesticated” aphids, mealybugs, and other honeydew-producing pests, protecting them like cattle while harvesting the honeydew as a food source. This means your mealy predators could be in for a fight.
An easy solution is to sprinkle diatomaceous earth around the base of the infested plants. Known as DE, this substance is actually the crushed fossil shells of microscopic diatoms.
Food grade DE is perfectly harmless for you and your pets (although you don’t want to breathe it in), but dust becomes a jagged minefield for insects.
The DE will lacerate any ants that try to crawl over it, causing them to dehydrate and die.
This simple barrier will need to be replaced every few days and when it rains, but it will allow natural predators to focus on eliminating the mealybugs without being at risk of an ant attack.
Neem Oil
We talk about this remedy because it’s highly effective and non-toxic (except for some aquatic creatures).
To combat mealybugs, you can either use the clarified form with emulsified water (basically just water with a tiny bit of Dawn or castile soap) as a foliar spray or the pure form with emulsified water as a soil soak.
The foliar spray works on contact and dissipates in about an hour without leaving any residue. However, it must be applied at dusk or Dawn to avoid harming beneficial insects.
Apply every other day for 14 days or until the infestation is gone and may be used every two weeks as a preventative.
Meanwhile, neem soil soaks are absorbed into the plant, disrupting the hormones of any insect that tries to pierce or chew the plant.
This systemic insecticide remains effective for up to 22 days and should be applied every 3 weeks until the infestation is gone (or as a preventative).
While few plants are known to be sensitive to neem, always test a tiny portion of the plant 24 hours before beginning treatment to be safe.
Soapy Water
Like insecticidal soap, Dawn dish liquid or pure castile soap can be added to water to create a bug-killing spray.
When the soapy water hits a mealybug, it clogs its airways, causing them to suffocate.
After a few hours, you can spray the plant with water or wipe the leaves to remove the dead bugs.
Keep in mind, however, that some plants are sensitive to soap, so always test a small portion of the plant before using this method (or any other one involving soap) to ensure it won’t harm your plant.
Coming Up With A Battle Plan
Now that we’ve discussed several methods, you can think about ways to mix and match for the best results.
Neem soil soaks work incredibly well if you’re using natural predators, as the neem won’t harm your friends while causing the mealybugs to become infertile – an excellent one-two punch.
Best of all, these two methods can be used throughout the growing season.
If you want a more hands-on approach, consider alternating between a neem foliar spray and wiping your plants down with a soft cloth dampened with isopropyl alcohol.
Alternatively, you can use the soapy water approach at dusk and some other spray at dawn to tackle a horrible infestation.
Don’t be afraid to experiment with combinations to find out what works best for your garden’s circumstances.