Get down and dirty in the garden
iHola Taylor! I’ve had a kalanchoe plant for several years, but I noticed today that I have all these little white and green buggy … THINGS … on the leaves. And a LOT of them! They kind of look like little crustaceans, but they’re so small it’s hard to describe them. White, crustaceany, things, I guess. How do I get rid of them? – Bárbara from Florida
I had a feeling about Bárbara’s infestation, and when I sent her this photo, she said, THERE THEY ARE!
They’re aphids (Aphidius colemanii). And aphid skin casts (observe the white shells). Aphids come en masse between seasons and reproduce fast. Also, they secret a substance called honeydew, which can attract both ants and sooty mold.
CURE: Bárbara, the first thing I would do is to take the plant outside and spray it off with your hose’s jet setting. Or if you don’t have a hose, get one of those cans of air (that are so fun to play with) and knock off as many aphids and their casts as you can.
Then move the kalanchoe to an isolated location away from any plant close enough for an aphid migration via air current. If you only have a garage or a dark location available, you can buy a compact fluorescent bulb which is labeled “natural sunlight” or “natural light” as a sort of make-shift grow light.
Next, mix some rubbing alcohol with water in a sprayer – 1 part alcohol, 2 parts water – and spray on the plant leaves daily in the morning, making sure to get under the leaves, in the plant crevices and on the stems without over-misting.
Aphids are attracted to yellow, so rub Vaseline on some Post-Its and circle them around the base of your plant. Change daily, and when you notice no more insects, you’re probably safe.
WHY THIS WORKS: In the US, what we call rubbing alcohol is also called isopropyl alcohol or more scientifically, isopropanol.
Kalanchoes are succulents that don’t have a high tolerance for pesticides or humidity (both which can be super-effective for destroying infestations). So isopropanol is ideal, because it’s cheap, doesn’t stink, dries quickly, is relatively non-toxic and it leaves the waxy shine so important in indoor ornamental kalanchoes.
Isopropanol cuts through lipophilic substances, like oil, which is why it’s so great at removing that smudgy gunk on your eyeglasses. When bugs come into contact with it, the waxy cover of their skin is dissolved, and they are poisoned.
This poisoning works the same in humans, but only in much larger doses. When the isopropanol hits the liver, it is oxidized into acetone (finger-nail polish remover). Yikes, huh? But, every year Americans use 500 million pounds of toxic pesticides wayyy worse than isopropanol.
Because it dries quickly, it’s diluted and you won’t be soaking your plants in it, misting will be safe for you and your kalanchoe – just not for your bugs.
(CAUTION: If you notice other white or cotton-bally insects growing on your plants, it may be a sign of a more serious infestation.)
If you’ve got a problem, I’ve got a solution – shoot an email over to Taylor at firstname.lastname@example.org.