brown spots on leafs

underside of leafs...it looks more than just dust collecting...

Recently I acquired a new Calathea and upon bringing it home I gave the plant a wipe down. I found there are what looks like tiny tiny specks of dust on the underside of the leafs so I wiped them off but as I was cleaning, I also noticed TINY TINY WHITE BUGS crawling on the stems of the plant, there wasn't many of them and they're quite small (didn't look like cottony mealy bugs, nor did they have webs so that should rule out spider mites) but I have a feeling that it could be aphids, because I checked the leafs and they had these type of markings on them, which doesn't seem normal for the plant. I had asked the previous owner and she told me that she's never had a bug problem in her home, but it seems maybe they're just too small and were missed.

Any ideas of what they may be? My bets are these are done by perhaps Aphids?


2 Answers 2


Other option could be thrips based on that you have seen tiny, tiny insects. There are many species but most commonly they are white and very tiny as said.

In my experience they are very hard to notice if you do not know what you are dealing with. Chances are high that you will see the browning spots and other damage on your plant first.

Note that fully grown thrips can fly so you want to somewhat isolate the infected plant from the rest of your plants. I find these bugs very aggressive they can cause a lot of damage in a short time. I usually treat the infected plants with Neem oil mixed with water and dish soap, but still fighting them can be a struggle sometimes stretching over weeks.

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  • I haven't noticed any flying ones, just ones that crawl along and they're kinda in a more rounded shape than these. Regardless, I just gave the plant a shower treatment of soap and water then cleaned every single leaf on the plant, which wasn't easy. I also updated the images to show you what I mean with the underleaf situation :)
    – TofuGrower
    Commented Dec 18, 2020 at 18:52
  • 1
    @TofuGrower If more rounded then it might be actually aphids. Also I have never seen thrips fly because they are so small, they just "magically" appeared on other plants. :D I hope your bugs will be gone, but I would treat the plant a couple of more times just to be sure in the upcoming weeks. :) Commented Dec 18, 2020 at 19:10

SOLVED: I diagnosed this, it's Spider Mites which Calatheas are quite prone to. If you're noticing these marks on your Calatheas, please take action and get them cleaned ASAP!

  • I think now you can accept your answer. :) Commented Jan 6, 2021 at 12:52

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