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My Cussonia bonsai suffers from these pests which I cannot recognize. I cleaned the leaves with a 90% alcohol solution, but they keep coming back, although I don't know if those are new pests or just eggs that are hatching.

Could you please help me to recognize those pests? I'd appreciate any advice on how to treat them?

Image of the pests

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They are aphids and soap and water will deal with them effectively. See here for more details. For a bonsai you do not want to take the risk of burning the leaves so be sure to rinse the leaves a few minutes after spraying.

The key to control is to spray at least three times at five day intervals. This will catch the newly hatched young of the next generation.

Edit: either method works well. It depends on the number and size of leaves. Many small leaves would make spraying easier. Using a paper towel to rub the underside of the leaves does take care of the eggs as well but takes longer.

Edit: to remove the soap I would spray it with water. If you want to remove it with a damp paper towel you will have to do it a number of times to reduce the residue level.

Just remember: only 5 ml of soap to a liter of water, a little goes a long way

Edit: it doesn't really matter what soap you use. As you are dealing with a soft bodied insect all kinds of soap will do the job. All soaps are fatty acids and dish soap works just as well as "Insecticidal soap". Use the simplest plainest type you have.

  • Thanks for your reply! I need to spray the water with soap? Or can I soak a paper towel in it and rub each leave? – user1895 May 7 '14 at 19:50
  • Thanks for the extra info - Do I need to rub it one time with soapy water, and then again with clean and damp paper towel in order to remove the soap? – user1895 May 7 '14 at 19:55
  • Thanks a lot! Sorry I cannot vote up your answer because I don't have enough points here. By the way, which soap shall I use? I understand that liquid soap is needed - Hand soap? Or body soap? I'd rather use an organic, no SLS soap actually. – user1895 May 9 '14 at 6:56
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I don't think you should be using alcohol...could damage the leaves of your bonsai. Aphids or whatever, they look like soft-bodied insects that NEEM would be able to handle, safely. Great product in my opinion, so far. Still!!! Read the LABEL, 5X. Indoor plants seem to need even more vigilance than outdoor where insect opportunists are concerned.

Or, possibly a soap spray...even just water spray? How long have you had your bonsai? I used to put pot and plant in a water bath (or a shower in my shower) each time I watered. Wash off dust as well as eggs, larvae and adult insects. Then allow to dry out (one or two days with a bonsai). You shouldn't have much trouble, the main thing is you are vigilant!

  • Thank you for your reply. I have the bonsai for more than 4 years. Do you rub leaves individually as well when you spray water on it regularly? (I water it every 2-3 weeks). – user1895 May 7 '14 at 19:52
  • No. Rubbing can ruin the skin of your leaves. Just allowing the water to wash off the leaves is enough...for bonsai I watered with a pail of water big enough to put the entire plant into the water and let it soak. Spray from your shower might be too much and will wash away your sands/soil. Use a humidifier or keep a pot of water on the stove simmering to increase the humidity in your home. Otherwise you can use a huge tray with pebbles and water underneath your bonsai to help with humidity. Spray with an antidessicant(?) Like putting on a little raincoat to slow transpiration. – stormy May 11 '14 at 22:38

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