Help us keep our orchid alive!

November 10, 2020 3:42 AM

Yesterday, we noticed a few tiny white bugs (1-2 mm) in the bark mix around the roots of our Phalaenopsis orchid. Our best guess is they're root mealybugs, but frankly, we know nothing about plants. The orchid is two years old and needs repotting anyway, but we'd been waiting; it's finally blooming again and we didn't want to risk damaging the flowers. How can we get rid of the bugs? Difficulty level: we're completely ignorant. It's remarkable we've kept the plant alive this long, so we'd like to continue doing so!
posted by kyrademon to Home & Garden (4 answers total)

They are probably aphids.You can use a weak soap solution to spray the bugs without damaging the plant. I use a prepared spray- I think the brand is Safer but you can use castile soap like Dr Bronners. You may have to do it a few times to get rid of them. If you have other plants you may need to treat them also.
posted by bookrach at 3:54 AM on November 10, 2020

If you can find a praying mantis in your garden, put it on your orchid. Those things are the face-eating leopards of the insect world.
posted by flabdablet at 4:20 AM on November 10, 2020

If they're tiny and white and rapidly crawling and non-fluffy AND they're only in the potting medium and not, say, on the undersides of leaves or the crooks and crannies or "crotch" of the phal AND your bark mix is breaking down, then you may have springtails rather than aphids or mealybugs. Springtails only eat rotting organic matter, like rotting bark, and are considered fine to have in plants, although in a phal, I'd consider it a serious sign to repot into fresh mix without delay (They are sometimes intentionally introduced into terrariums to control rotting organic mater and prevent mold/plant diseases. As a side note, I would never, ever, ever bring a praying mantis indoors, both because it's cruel to the mantis since my house does not have enough bugs to feed it, and because it's cruel to humans due to, uh, mantis egg sacs. They ain't gonna do shit against most insect pests to houseplants, either.)

If they're mealybugs, and they're bad enough that they're in the roots, it may to be a tough fight, especially because your plant is in bloom. The best way to treat a phal with root mealybugs is to aggressively treat for mealybugs, then repot. Either of those can cause a phal to abort its flowers, especially if they are still in bud. You can wait until the bloom is over, but this creates the risk of the mealybug infestation continuing to spread unchecked for a month, and then the mealybugs attacking the weakened plant.

If you want to keep the flowers, then I'd do as bookrach says to keep the mealybugs at bay while the flowers bloom. I also use rubbing alcohol with a q-tip to get into crannies, and you can get houseplant insecticides at big box stores. However, these are only temporary measures to vaguely attempt to control the mealybugs that you can see with your eyes.

For long-term treatment if you have mealybugs in the ground, you're going to need to take more drastic measures -- once the flowers have faded to a point where you're OK with them going and without cutting the stem*, I'd do this this and then repot it into completely new, fresh out of the bag potting mix in a completely new pot, preferably in a completely new location, just in case any mealybugs were on vacation when you grabbed the plant for repot. There are lots of videos online about how to repot phals. And I'd probably keep the insecticide and rubbing alcohol on hand for a while after, just to make sure.

If this really is root mealybugs, and this is a treasured phal, I'd probably just treat it and give up on the flowers. Dead plants can't bloom again. I fucking hate mealybugs.



*I would not cut the stem while it's green because 1) with phals you're supposed to leave the stem until it dies back, and 2) if you cut a green stem, there's a chance that rot and infection will infect the plant and get down into the crown, and boy, mealybugs are tough, but saving a weakened, post-bloom phal from crown rot while still battling mealybugs is even worse.
posted by joyceanmachine at 5:55 AM on November 10, 2020 [3 favorites]

If they are mealybugs, dedicated once or twice daily removal of the adults you can find with tweezers with a close full top to bottom inspection will control a medium-low level infection if there aren't too many living out of reach in the medium. There will still be eggs so you have to keep this up for weeks, but I have gotten rid of a low level infection with nothing but dedicated hunting until there are no more reproducing adults, ymmv. If the orchid is not otherwise too stressed by any watering or fungal issues, and the mealybugs are not too numerous, you might be fine with just this.

Neem oil is also good; its organic, safe around people and pets, mildly antifungal in addition to deterring insects, and it's derived from a plant. Its noxious to just about everything but the orchid. Repeat application at several day intervals is key and I would try to keep it off the new buds and only get the leaves and top of the medium. Don't skip the leaf undersides or the crown, but phals are notorious for dropping buds if you so much as look at them funny.
posted by slow graffiti at 11:11 AM on November 10, 2020 [1 favorite]