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Yellow bugs working with black balls on my cacti

gergo5hwyVjxDgergo5hwyVjxD Posts: 9
in Problem solving
Hi!

I’ve noticed black balls on my cacti, but wasn’t able to see anything moving. Bought some special lenses to my camera to have a closer look.

They look like this:


I was doing some research, and haven’t found anything similar, especially with the black balls.

They probably thrive on the juice inside the plant, as the plant often releases white liquid:


So the question really is what are they, and how can I get rid of them? I already sprayed with diluted rubbing alcohol earlier this week, it seems it wasn’t effective enough.

Posts

  • DovefromaboveDovefromabove Posts: 88,147
    Could the black balls be droppings from an insect larvae or similar?

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.





  • gergo5hwyVjxDgergo5hwyVjxD Posts: 9
    They must be related to each other, but haven’t seen anything like this yet.
  • wild edgeswild edges Posts: 10,497
    gergo5hwyVjxD said:
    They probably thrive on the juice inside the plant, as the plant often releases white liquid:
    There's your number one clue that your plant isn't a cactus. It's a euphorbia and that white sap is fairly toxic stuff so don't touch it if you can avoid it. Try using soapy water to spray the plant and see if that helps. I would spray the plant with soap in the morning then rinse it off later with clean water and dry it out the best you can. Cover the soil with plastic so it doesn't get too wet. When the weather warms up you can do it outside but best to avoid too much damp at this time of year.

    If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
  • clarke.bruntclarke.brunt Posts: 215
    edited February 2021
    As @wild edges says, not a cactus, but a Euphorbia. I'm thinking maybe red spider mite and their droppings? That gives something to look up on the web, but the usual kind has two black marks on their body, and this only seems to have one? I know we can't see much of the plant in the photos, but what I can see looks in a bad way - in the 2nd photo (sideways) at the right is a sturdy-looking stem, which is still green, and then extending leftwards from it what is probably relatively new growth (e.g. during last season), which is very thin by comparison, and discoloured whitish, probably by the bugs. Don't know if they're still alive or not. The weak and thin new growth suggests grown in insufficient light, or kept warm over winter, and weak growth would be more susceptible to the pests.

    As mentioned, Euphorbia sap (latex) isn't good for humans (it wouldn't normally exude from the plant unless part of the plant was damaged or broken). Doesn't necessarily mean it's toxic to pests, though I don't think I've ever seen a pest on a Euphorbia before.
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