If you grow succulents, sooner or later you'll deal with mealy bugs. For newbies, they may come as a surprise. Suddenly the plants are dotted and webbed with what looks like lint. Veterans are more vigilant. We check for mealies routinely and halt the spread early, before it's severe.
Here's how to deal with early and advanced infestations.
Inspection and Treatment
Check for mealies in the centers of rosette succulents, in crevices, and in leaf axils (where leaves join stems). Unlike aphids and thrips, mealy bugs usually don't colonize flower buds. In my garden, mealies tend to be more prevalent in summer and fall. Ants transport and "farm" the pests for their sweet secretions.
Treat by spraying with 70% Isopropyl alcohol (use 70%; 90% is too harsh). I buy a 32-oz bottle at a supermarket or drug store and add a spray attachment from an empty bottle of, say, Windex. (Btw, some growers use Windex to control mealies and other pests.) If you're treating a delicate succulent, play it safe and dilute the alcohol half-strength with water.
Drenching the bugs with alcohol kills them on contact and their eggs as well. Although it may temporarily dissolve the leaves' powdery coating, I've yet to see alcohol have a lasting impact on the plant.
Isolate affected plants to keep pests from spreading.
When an Infestation is Severe
From my site's Pest Forum: An exchange with Kristi, a newsletter subscriber in Denver. She writes:
Q: Help! I'm at my wits end with an infestation of mealy bugs on my beloved Jade plant. I’ve sprayed with 70% Isopropyl alcohol repeatedly and still have a problem. Not too mention hard to spray in the shower with the smell! There is damage/scarring where the leaves meet the stem and in the middle of some of the leaves. The plant is very big and dense so its difficult to spray into the middle and hit all the leaves and underneath. The plant is very heavy but we do have some warmer weather this week that I can take it outside to spray the plant with alcohol heavily. Short of cutting off every leaf, is there anything else I can try? Is there a safe systemic insecticide to try?
A: Once a mealy bug infestation gets that bad, conventional wisdom is to get rid of the plant. But this one is important to you, so here are some things to try:
- Take it outside on a warm day (above 40 degrees) and hose it down. It’s OK if some leaves fall off. If they’re that loose, they probably will anyway.
- Repot it. Mealies can get in the soil.
- If that’s not possible, fill a bucket with water and add systemic insecticide “for sucking insects” per label directions. Wear gloves. Brands available on Amazon include BioAdvanced and Monterey Systemic Soil Drench.* (Both are used for food crops, so they're relatively "safe.") Let the pot sit in the bucket until the soil is soaked—an hour or so.
- After the plant is hosed and/or soaked, drench its leaves and stems with dilute insecticide. Let dry before bringing it back inside.
Prevent a Recurrence
- Do NOT put the plant back where it was. Regardless, DO clean the area thoroughly, because mealies can hide in, and lay eggs in, the tiniest crevices.
- Indoor plants can be breeding grounds. Get rid of or isolate any that have the problem. Treat with alcohol. If plants are severely infested but worth saving, follow steps above.
- Good air circulation is key to keeping mealies and other pests from settling in. To help it recover over the winter, you might put your jade under full-spectrum lights and use a fan (both on a 12-hour timer).
- Consider thinning it out so air circulates through the plant. Jade cuttings are as good as having new plants, they’re that easy to start.
- Keep me posted on the patient’s progress!
Related info on this site
Are pests or mysterious maladies causing problems with your succulents? This page is a forum for you to ask questions, leave comments and share what works for you. Others can see and benefit from the answers. Your own tried-and-true solutions are welcome, too!
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