Does anyone know what the little blackish/dark greyish insects are that
sometimes live in soil (usually around sickly plants)? They jump about a
bit if disturbed (they're not fleas). I've always thought they were
springtails but I now realise these are white. Do the little jumpy things
cause damage? If they do, how do I get rid of them and prevent them from
arriving in the first place?

TIA
--Alison

They're probably a fly. I added a load of compost activator to a large
container of garden waste and on opening it some time later found it to be full
of white flies which jumped (or maybe flew) around. I have a feeling that the
compost activator may have had large numbers of dormant fly eggs in it. When
these get damp the larvae/maggots start to chomp through the garden waste
speeding decomposition. Then again, the flies may have just been introduced
naturally along with the garden waste before it was all sealed up in the
container.

I'm not sure as this will help, but it might give you another avenue to look
down.

As for getting rid of them, I'm not sure you really need to. They probably
just help break down matter that's already dead. If for some reason they're a
problem/nuisance, try a general purpose insecticide. Someone on here may be
able to suggest something non-chemical that is more environmentally friendly
though. I'd suggest you consider just leaving them well alone though. They
won't last for too much longer if the weather changes.

All the best,

Dave.