I recently planted a mint plant purchased from a supermarket in some houseplant potting soil. It's been on a windowsill in the kitchen. In the last week it's acquired some sort of pest which I've tried to take photos of (below).

I have no problem throwing it away and starting again since the plant was very cheap, but I'd like this not to recur. Hence:

  • Can anyone identify what this is likely to be?
  • If I were to ignore it, what would be likely to happen (for example, would it go away, kill the plant, spread to other plants in my flat...)?
  • What precautions should I take to avoid this happening to its replacement?

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2 Answers 2


I can see what might be black insects on some of the stems, but can't see them clearly. I can also see some white, oblong objects or marks on top of a leaf about halfway down on the left hand side of the second photo - again, its not possible to see them clearly.

These might just be aphids (blackfly) in which case it's worth spraying with an insecticide suitable for edible plants. These may have been present on the plant already when you bought it, or, if the weather outdoors isn't cold and you've an open window nearby, they could just have alighted on the plant from outdoors. If it is blackfly, yes, they will spread to other plants you have indoors.

  • From where do aphids come? Soil? I don't think they can fly. And somehow they re-emerge.
    – 4-K
    Feb 18, 2020 at 16:25
  • @4-K - where aphids come from is already covered in my answer. Aphids can and do fly.
    – Bamboo
    Feb 18, 2020 at 16:39
  • But it's strange cause they are flying so high (fifth floor) and no matter what I do, they never fly away.
    – 4-K
    Feb 18, 2020 at 16:45
  • @4-K - it seems your queries are not related to this question, so you'd better ask a separate question, although, if these flies you see are not on plants, then probably Biology SE is the place to ask.
    – Bamboo
    Feb 18, 2020 at 16:50
  • Nah! They are on my umbrella plant now. I crushed each one of them. But they still come. I don't think my question is worth asking as a separate one cause it's going to be closed for too broad.
    – 4-K
    Feb 18, 2020 at 16:56

looks like aphids

luckily to get rid of them you have a few options available

I would recommend using soapy water first simply mix non toxic washing up liquid with water then spray all over the plant from top to bottom. making sure you spray under the leaves as well.

the soap bubbles will suffocate the aphids.


if you also want you can use vinegar mixed with water 1/3 vinegar 2/3 water and spray them it will kill them immediately adults and larvae alike.

to prevent this from happening again

keep windows closed as they will fly in and always quarantine/wash thoroughly any new plants as they might have a hitchhiker on board.

also keep predator insects like Centipedes and ladybugs as they will eat the pests for you and prevent them from getting out of hand

I have a Centipede enclosure where I place any new arrivals (washed plants) and the Centipedes get to work in the dark for me .

it happens to the best of us :) so its important to by strict with the system you develop.

also you can use a TINY drop of neem oil mixed with a jug of warm water and spray all over everything even the soil but I wouldn't recommend that indoors as it smells bad so wear gloves.

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