Mealy Bug Mayhem (and Scale Onslaught)

Once our high temperatures get to 90 and above, I’m never surprised to get a lot of images in my email that look like these pictures.

It’s what I affectionately refer to as “Mealy Bug Mayhem.” I believe the wicked combination of tons of moisture followed by oppressive heat is what brings on these pests, and their more stubborn siblings, scale.

I'm not sure, from an entomologic standpoint, why this always seems to be the case. But with our recent wacky weather — super wet to super dry, then semi-moderate to stifling heat — I've never had so many calls and emails about them.

Most of those who contact me don't know they are dealing with insects. I’m usually asked about a “white, cottony fungus.” Or, with scale, they ask about a “black fungus with the white dots all over.” Here’s a scale tip sheet I’ve posted several times over the years, if that’s what you think you have.

Mealy bugs are white, soft-bodied insects that suck plant juices, and they are related to the family of insects that include scale. In fact, mealy bugs are just a soft, cottony version of scale.

Mealy bugs are often found nestled in the nooks and crannies of plants, where it's hard to spray. Most commonly, they attack new growth, so they are usually found near the growing tips and where leaves join stems or along leaf veins. They are covered with white, waxy threads that protect them from predators and give them the fuzzy appearance. Many listeners describe them as looking like snow or a white, furry fungus.

By the way, I'm not immune to these things. The single tree leaf pictured to the left in the top image is from my property. It's actually on my neighbor's hackberry, but half of the canopy is on my side.

The others are also from my place. It's a mass of mealy bugs on a prized hibiscus that was ignored for only a week. That should give you an idea of how quickly they can spread in the absence of a control. Although malathion is the hands-down best method for controlling scale and mealy bugs on evergreen plants and trees, BEWARE! It is awful on house plants, hibiscus and other tropicals. You should NEVER, EVER, EVER spray malathion on tropical plants. Always read the malathion label to be sure the plant you want to spray is not listed.

Meanwhile, there are other insecticides and organic remedies that will work. In my landscape, for example, my bulbines were being overwhelmed by mealy bugs. So, I have been spraying them down once a week with an organic spinosad. On the hibiscus pictured above, I just blast them off each and every morning with a jet of water.

For minor infestations on house plants, the best technique seems to be cotton swabs dipped in rubbing alcohol along with an application of soapy water. But remember, to make this an ongoing routine, because the eggs are often not eliminated with organic controls. And you have to break the egg cycle to be successful. Bottom line: Be consistent in your care, and check bug-prone plants regularly. These insects are under a protective hairy covering, so making direct contact with a pesticide is difficult. And a once-a-week approach is important.

For highly sensitive plants that can't take malathion, here are two homemade controls. Both have worked with varying degrees of success on tender plants. One of them should work for you.

Randy's Homemade Mealy Bug Control

I designed this formula nearly 17 years ago for tropicals on my back patio that were infested with mealy bugs. We had just welcomed our first child, and I was obsessed with keeping the patio 100 percent organic. I knew soapy water and rubbing alcohol worked on mealy bugs. And I added orange oil and neem oil as natural insecticides. Warning: Before you spray it randomly all over a sensitive plant, test it first on an out-of-the-way leaf to be sure it works without harming the plant. You should monitor the tested spot for at least 24 hours before you use it more liberally.

Mix in a one-quart sprayer:

  • 1 tablespoon of neem oil
  • ¼ to ½ cup of rubbing alcohol
  • 3-4 drops of orange oil
  • 4-5 drops of dish soap
  • Fill the rest with water

GardenLine's Homemade Scale Control

This version of a scale control has also had varying degrees of success in Gulf Coast landscapes, and it’s an alternative for Mealy Bug Mayhem. Remember, though, that organic controls must be used way more often than synthetics, if you hope to break an insect’s egg cycle.

Mix equal parts of ...

  • Agricultural molasses
  • Garlic oil
  • Seaweed extract

I prefer 1 cup of each in a one-gallon sprayer, but you can go with ½ cup if you want. It will smell bad, but the odor goes away in minutes. And, in addition to a natural insecticide, you get lots of great soil-building elements dripping from the plant down into the soil below. Some will claim that’s actually why homemade organic controls really work: the healthier the soil, the healthier the plant. And the healthier the plant, the more it can naturally fight off insects and disease.