Wednesday, January 15, 2014

Mealybugs, you vex me!

Yesterday I blogged about the plants I’m keeping inside for the winter. One of them is a small Duvalia corderoyi, which I won at a raffle at the Sacramento Cactus and Succulent Society. Duvalia corderoyi is a stapeliad, related to both Stapelia gigantea and Huernia zebrina, both of which bloomedfor me this past summer (see here and here). Duvalia corderoyi has equally beautiful flowers, and I can’t wait for it to bloom.

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Duvalia corderoyi flower. Image source: Wikimedia

Imagine how annoyed I was this morning when I discovered that my Duvalia corderoyi shows signs of mealybug infestation:

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I swear the tell-tale fluffy deposits weren’t there the other day! But then, I know from experience how quickly these little buggers can multiply.

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Mealybugs are the bane of my existence as a succulent collector. Some plant groups are more prone than others, but I deal with these nasty leaf suckers every summer (they thrive in warm weather). In fact, last summer was the worst I can remember. I was constantly spritzing plants in an effort to keep the mealies away.

Fortunately, mealybugs are easy to kill. You just need to spring into action at the first sign of an infestation. My remedy of choice is straight 70% isopropyl (rubbing) alcohol. This works great on many succulents, especially those with a thicker epidermis. However, straight isopropyl alcohol can mar softer leaves, like those of echeverias. For those plants, it is wise to dilute it with water.

Since this is my first Duvalia I wasn’t sure how well it would tolerate 70% isopropyl alcohol. To be on the side safe, I diluted it 1:1 with water and added a teaspoon of Dr. Bronner’s Pure-Castile Soap (I like the peppermint-scented variety). Soap helps break down the waxy coating that protects mealybugs so the alcohol can kill them more efficiently.

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I first loosened the mealybug cocoons with a toothpick and then sprayed the whole plant liberally with my magic solution. Here’s what my Duvalia corderoyi looked like afterwards:

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Nice and clean and hopefully free of mealybugs. But I’ll be on the lookout because the buggers often hide in the soil.

14 comments:

  1. Hide in the soil, I've always wondered where these bugs hide then spring a surprise again....

    70% isopropyl alcohol is not available here but we use methylated spirits to as good an effect! just not sure what composition it has but I can imagine very similar

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    1. I'm sure you can use any kind of alcohol. A 2-pack of isopropyl alcohol (2 x 1 liter) is only $3.59 at Costco, so that's what I use. As Hoover Boo says below, fancy liquors work too :-).

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  2. I'm pretty sure the soap alone will do the trick -- once the bug's waxy coating is weakened, they desiccate pretty rapidly. At least that's how I understand insecticidal soaps to work. Doesn't the soap itself present a risk to some succulents? I'm always afraid to spray mine with anything the first time!

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    1. Hey, if soap alone works, then soap + alcohol works even better. That's my philosophy :-).

      In hot temperatures the risk of leaf damage from soap or alcohol is higher, from what I hear, but I've never had any bad experience, even in the middle of summer.

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  3. Guess I better hustle downstairs and take a look at my prisoners.

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  4. Beautiful, beautiful flower on that Duvalia.

    Mealies are a big problem here also. I've discovered that Stolichnaya or Chivas Regal works just as well as isopropyl. We do like to pamper our plants, don't we?

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    1. Wow, you are a connoisseur pest killer! If any of my agaves ever had mealybugs, I'd use straight tequila to kill them. I think that would be poetic justice. Fortunately, agaves seem to be quite immune.

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  5. I have some of that soap and never thought of adding it to the alcohol. Thank you for the tip. And I agree that last year was the worst ever for mealy bugs. I have no idea why. I have already sprayed some plants this year too. Arg!

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    1. Candy, that Dr Bronner's Castile Soap is good for a myriad things. You can even use it to wash your hair--at least according to the label, LOL.

      I just found mealies on my Melocactus azureus that I'm also keeping indoors. Out came the spray again!

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  6. I googled mealybugs and found this post, Gerhard. This summer I'm getting them on some agaves! Crazy...

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    1. Lol. It's an old post but it's still the remedy I use. The key is repeated application.

      The mealies aren't as bad in my garden this summer but several cacti are showing signs of infestation. I've been spraying them...

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  7. I recently got a large pot of succulents containing a variety of succulents. One of the succulents now has mealybugs =( They're hard to get rid of! I thought I got them all but now they're back and it looks like they've spread to a neighboring plant. How long does it typically take to get rid of mealybugs when spraying them with alcohol?

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    1. You need to repeat regularly for a while--maybe once a week for a month--to kill not only the active adults but also any babies that will hatch. Good luck, mealybugs are the worst!

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