I think it was about this time last year that I issued a warning about “Mealy Bug Mayhem.”
I believe the combination of a very wet early August followed by temperatures exceeding 95 degrees is what brings on mealy bugs. And scale, their more stubborn siblings. I'm not sure just yet why this seems to be the case, but I've never had so many calls and emails about mealy bugs. And now I’m starting to hear about an uptick in the scale population, too. (Here’s a previous tip sheet on scale, if you think that’s what you need to control.)
Most people don't realize they are actually asking about insects. The questions I get are usually about a “white-cottony fungus.” Or a “black fungus with white dots all over.”
Mealy bugs are white, soft-bodied insects that suck plant juices. They’re part of the family of insects that include scale … in fact, mealy bugs are just a soft-cottony version of scale. They are often found nestled in the nooks and crannies of plants, where it's hard to get at them with a spray. Most commonly they attack new growth, so they’re usually found near the growing tips, where leaves join stems, or along leaf veins.
The bugs are covered with white, waxy threads that protect them from predators and give them the fuzzy appearance. And that's why most of my calls and emails have described the problem as looking like snow or "a white furry fungus." By the way ... I'm not immune to these things. The single tree leaf pictured on the left below here is from my property. It's actually my neighbor's hackberry, but half of the canopy is on my side and that’s where I found this example.
The other example is also from my place. It's a mass of mealy bugs on a prized hibiscus that was ignored for only one week. That’s how prolifically they can procreate in the absence of a control measure.
Malathion is the hands-down best method for controlling scale and mealy bugs on evergreen plants and trees. BEWARE, though … it is awful on house plants, hibiscus and other tropicals. So, NEVER, EVER, EVER spray malathion on tropical plants. Always read the malathion label, and make sure the plant you want to spray is not listed.
Meanwhile, there are other insecticides and organic remedies that will also work. In my landscape, for example, my bulbines were being overwhelmed by mealy bugs. I have been just spraying them down once a week with an organic spinosad. On the hibiscus pictured here, I just blast off the mealy bugs each and every morning with a jet of water.
As for minor infestations on house plants, using cotton swabs dipped in rubbing alcohol along with an application of soapy water seems to be the best technique. But remember ... this needs to be an ongoing routine, because the eggs are often not eliminated with organic controls. Bottom line: Be consistent in your care, and check bug-prone plants regularly. These insects are under a protective hairy covering, so direct contact with a pesticide is difficult. And since the organics may not work well on egg cycles, a once-a-week approach is always important
For highly sensitive plants that can't take malathion, below 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
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
I originally designed this formula, nearly 14 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 back 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 give the “test treatment” at least 24 hours of monitoring before you use it more liberally.
And finally, here’s a homemade scale control that has also seen some success in Gulf Coast landscapes. Just remember that organic controls have to be used more often than synthetic controls to break an insect’s egg cycle.
GardenLine's Homemade Scale Control
Mix equal parts of ...
- Agricultural molasses
- Garlic oil
- Seaweed extract
I prefer 1 cup of each in a one-gallon sprayer, but if it makes you feel safer, go with ½ cup. While this can initially smell bad, the odor goes away in minutes. And not only do you get a natural insecticide, lots of great soil-building elements will drip from the plant into the soil below. Some will tell you that’s really why homemade organic controls work. The healthier the soil, the healthier the plant, and the healthier the plant, the better it can fight off insects and diseases.