Bonsai Care - How to treat Aphid (Blackfly and Greenfly)

Aphids are a very common insect which can suck the sap on both indoor and outdoor bonsai trees, and most other plants. Both greenfly and blackfly are common examples of aphid.
We have had more e-mails this spring about aphid than ever before. I'm not sure if this is because it has been warmer and they are just more prevalent!

Symptoms of Aphid.
Usually the first symptom of aphid on a bonsai tree is that you notice a sticky residue on some of the leaves. This is the 'honeydew' from the insect and sometimes a black sooty mould will develop as a result.

If you look closely you may be able to see small black or green flies underneath the leaves. When the aphids shed their skins and moult they can leave white skins on the leaves or soil.
Aphids can cause stunted growth or distorted and curled leaves on a bonsai. This can affect the health and weaken the bonsai so it is important to treat this pest.

We spray weekly with a plant invigorator as a preventative measure. This is an environmentally friendly product and is very effective.
However, if you are trying to treat aphids you may find a general insecticide is more effective; especially in the short term. Aphid is a very easy pest to treat with insecticides. These are available from most garden centres and are extremely effective.
Please follow the manufacturers instructions but a repeat spray will be necessary to ensure any eggs which hatch are also treated.


4 thoughts on “Bonsai Care - How to treat Aphid (Blackfly and Greenfly)”

  • Richard holly

    Please help me its my first bonsai I am doing everything ive read in my books to do but my leaves r brown my problems started when I replaced the soil the tree came with I used proper bonsai compost ive been spraying my tree every morning watering him every 2 days using bonsai feed once a week on the same day ive left him in the kitchen by the sink in the window please help

    • Bonsai Direct
      Bonsai Direct 25th May 2015 at 8:25 am

      Hi Richard,
      Are the leaves going crispy?
      Did you replace all the soil? If so please do not feed for a month after re-potting (new compost will have some nutrients in it and you could scorch the roots if you give the bonsai too much feed.
      I would recommend standing the pot in water for 5mins so that the water covers the soil surface; then you know that the soil is evenly wet. You could have a situation where the original root ball is dry and the new soil is wet.
      I hope this helps
      kind regards

  • Marilyn Edwards

    My black flies are congregated(lots of them) on the moss covering my Larix bonsai.
    Can you advise me please?

    Kind Regards

    • bonsaidirect

      Hi Marilyn,
      I would recommend spraying the moss with an insecticide and repeat spraying a week later.
      Kind regards

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