Black and green flies on Tomato plants

[sall2009]

Yesterday I noticed that some of my tomato plants have green and black flies on them. The flies are on the stem and one or two were on the growing tomato too. Do these flies need to be got rid off? If s, how do I go about doing it?

[chris]

Green/black fly (aphids) most likely. They're in my greenhouse but not on my tomatoes.

Either squish them, or a squirty bottle full of water with a drop of washing up liquid (or/and a clove of glaric crushed some say!) will kill them. You'll need to repeat whichever method though, they breed extremely rapidly.

The soap in the water stops them breathing as they breath through their skin. I just run my fingers up and over them. If the infestation is bad, I pinch off the part of the plant and compost it.

They'll weaken the plant if they continue to reproduce, so yes they should be got rid of.

[chris]

...or thinking about it, if the black flies are shiny, and on the yellow flowers of your tomato, they could be pollen beetle, whch aren't an issue.

[Sylvan]

There seem to be clouds of greenly and blackly around at the moment. I find they're very easy to rub off the tomato plants when they're still in their winged stage - just run your finger over them. If they've started reproducing and you have colonies of the non-winged ones you'll have to squish a bit harder and it turns your squishing fingers green, so don't do it on your way out to anywhere important...

[Florence Fennel]

Or wear rubber gloves

[Nik]

I have noticed that I have lots of blackfly on my young tomato plants which are mostly repotted sideshoots, but none on my big, more mature plants. The young plants obviously secrete something the insects want but they stop producing it, or produce less of it, after they first flower.
I don't know if this is helpful at all but I thought it was interesting.

[Two_Sheds]

^ Aphids find it easier to suck sap from young plants, or from overfed floppy lush growth, rather than tougher mature plants