Mealybugs on Jade Plants

2022 March 13

A bit over a year ago, in January of 2021, Sandy started noticing that her jade plants (Crassula_ovata) were not putting forth new leaves properly. The leaf buds were stunted, deformed, and mostly died and fell off rather than growing out properly. And, looking at the plants more closely, she saw that there were small cottony growths mostly at the bases of the leaves.

Uh oh. This looks like some sort of sap-sucking plant parasite. A lot of them make this kind of cottony cover to protect themselves from drying out and hide from predators.

We couldn’t see much with the naked eye, so I went over it with the high-magnification macro lens. Checking the deformed new leaves (this leaf was about the size of my thumbnail), I saw some brown specks that moved slowly

And closer still, here is what we see:

Aaaaaaannnnd, they appear to be mealybugs. This is an entire family of insects (Pseudococcidae) that are common pests in greenhouses and frequently infest houseplants.

Mealybugs are emphatically not native to the upper peninsula of Michigan, they are a tropical family that mostly lives in humid, hot environments. And, unlike aphids, they appear to actually chew on the plants and cause mechanical damage rather than just sucking out plant juices. We spotted them digging into the leaf bases (they are circled on this next picture)

And they were also chewing on the margins of the young leaves

So. This was bad. They had infested almost all of our jade plants, and had brought their ability to grow new leaves to a screeching halt. The first thing we did is wash all the plants with insecticidal soap, which did set back the mealybugs quite a bit, but they kept coming back. It was looking like a losing battle.

But then, the winter ended. And we decided to try one last thing: In June, we moved all the jade plants out onto the porch. The idea being that (a) this is not the environment that mealybugs evolved for, and maybe the cooler temperatures at night would set them back without killing the also-tropical jade plants, and (b) maybe other, predatory insects would find and eliminate them. Mealybugs are not armored, and so are particularly subject to being eaten by things like lacewing larvae and lady beetles.

So, the jade plants stayed out on the porch all summer and into early October, at which point we checked them over carefully. And, lo and behold, we found no evidence of mealybugs, with new leaves growing in clean and undeformed! So I went over individual jade plants one at a time with a magnifying glass, and as each passed inspection they came back into the house.

Now, as of March 2022, we have gotten through the winter and still no sign of mealybugs, so apparently that was that. As for where they came from, every now and then we do get a new houseplant from WalMart, and they probably had an infestation.

If we lived further south, where it gets hot in the summer and the mealybugs can live through the year, this probably wouldn’t have worked. But it sure worked out well this time!

Comments are closed.