How to Identify and Control Root Mealybugs

Root mealybugs are a tough pest because they lurk within the potting mix and attack the roots of your plant.

A plant can appear healthy above soil for a long period time. It will only begin to show real damage in easily visible locations once root mealybugs have infested its roots.

Even worse, root mealybugs can spread between your plants and go undetected, creating huge infestations in relatively short periods of time.

Today we will discuss what root mealybugs are, how to know if a plant has them, and what to do about it!

Table of Contents

What are Root Mealybugs / What do Root Mealybugs Look Like?

Root mealybugs are tiny white insects that live at the root level of your plant.

They look very similar to the type of mealybugs that we find hiding in plant foliage, but are actually different bugs.

Photo by: United States National Collection of Scale Insects Photographs , USDA Agricultural Research Service, Bugwood.org

Root mealybugs feed off the plant by sucking sap out of the roots.

Many root mealybugs leave a waxy, powdery substance behind as they feed, which discolors the soil.

Photo by: United States National Collection of Scale Insects Photographs , USDA Agricultural Research Service, Bugwood.org

These pests are fast to reproduce and build a colony. Females can lay eggs daily and those eggs only take about a day to hatch.

Juvenile root mealybugs are often referred to as crawlers because they are able to move much faster and can easily crawl to other plants and infest them.

Adult root mealybugs can also move, but do so much less and at a much slower pace.

What are some signs your plant has root mealybugs?

  • The plant has stopped growing
  • The plant’s leaves are wilting or turning brown and yellow
  • The plant isn’t perking up after watering
  • There is white cottony build up around the roots of the plant

As with all pests, many of these symptoms are similar to other pests and common houseplant problems.

The key to confirming whether your plant has root mealybugs is to check the roots and look for the telltale white dusting or buildup around the roots.

If you use a magnifying glass you will be able to see the bugs themselves.

How to you control root mealybugs?

There are several proven methods of controlling root mealybugs:

#1 Soak the roots in hot water

  1. Remove and throw away the potting mix that the plant is currently in.
  2. Remove as much of the potting mix on the roots as possible.
  3. Soak the roots of the plant in water at 120 degrees Fahrenheit for 15 minutes
    • I’ve used a candy thermometer or meat thermometer previously to figure out the temperature of the water
    • Unfortunately the temperature may cool relatively quickly during the dip so you could consider switching the plant to a second cup of water halfway through that is back at 120 degrees Fahrenheit
  4. Soak the roots in cooler water (around 70 degrees Fahrenheit) for 10 minutes
  5. Repot your plant in fresh soil with diatomaceous earth mixed in
    • Diatomaceous Earth is a fine powder that prevents insects from being able to move throughout the soil without being damaged, which helps to eliminate any additional eggs or insects

Here is a link to the diatomaceous earth that I use (linked to Amazon through the affiliate program)

Nature’s Wisdom Food Grade Diatomaceous Earth 1 lb. Jar

Note: if you are using the same pot that the plant was in previously, it will need to be sterilized. You could wash it with soap and warm water, using rubbing alcohol, or other methods to remove any potential pests.

#2 Use a homemade insecticidal soil drench

The same neem oil and soap spray that is able to used on the foliage of a plant can also be applied as a soil drench.

Neem oil works by preventing the pests from successfully growing and molting while also decreasing appetite.

The combination of these affects eliminates the pests slowly, but effectively.

Also, when applied as a soil drench, the plant itself will absorb neem oil when taking up water, causing any pests trying to eat on any part of the plant to ingest neem oil and eventually perish.

To make the drench, mix:

  • 16 ounces of water
  • .5 tsp of neem oil
  • .5 tsp of gentle dish soap

Once mixed, your plant can be watered as normal. Reapplying every couple of weeks is recommended.

It is recommended to test products on one plant first, whether its used as a spray or a drench, to ensure it doesn’t harm your plants.

Some plants are sensitive to neem or soap. I’ve noticed some of my ferns do not take kindly to neem oil and become very burnt looking afterwards. Whereas my carnivorous plants are fine with neem oil, but cannot tolerate soap.

Here are the links to the neem oil and dish soap I use to mix by drench (all links are through the Amazon affiliate program).

#3 Use a systemic pesticide

Using systemic pesticides is always my last line of defense. Why? Systemic pesticides are not only toxic and unhealthy for the pests that you are trying to eliminate, but they are very toxic and unhealthy for us humans, beneficial insects, and pets.

To use a systemic pesticide, carefully read the directions for how much you need to apply to each size of pot. Mix the systemic into the potting mix and then water the plant thoroughly.

As the plant is taking up water through its roots, it will also absorb the systemic pesticide and become a toxic plant to any one who tries to consume it.

This effect can last for up to 3 months and does control a large range of pests.

I will link the systemic pesticide I use through the Amazon affiliate program below:

Bonide Systemic Houseplant Insect Control

How do you avoid getting root mealybugs on your plants?

The easiest way to prevent having root mealybugs is by looking at the roots of a plant before you buy it.

This is often easy to do as the plants can be lifted gently from their nursery pots to inspect the root ball.

In truth though, there is no guaranteed way to prevent them as potting mixes can have root mealybugs (or other pests) in them without you realizing. That is why observing and spending time with your plants is so important in early pest identification.

Can root mealybugs spread to nearby plants?

Yes, they can. Especially when they are in the crawler/juvenile stage, they are very mobile and can easily crawl between pots.

Big Takeaways

Root mealybugs are a sneaky pest that lurks around the roots of your plant

  • if your plant is wilting, turning yellow, or behaving oddly and you aren’t sure why, its time to check for root mealybugs

The only way to confirm whether your plant has root mealybugs is to inspect the roots

  • look for white cottony buildup in the soil or tiny white dots, which are the bugs themselves

There are several methods of controlling root mealybugs

  • a hot water bath for the roots
  • a homemade soil drench
  • systemic pesticide applications

If your plant is super infested, it is also completely okay to get rid of the plant to prevent others from being infected.

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