soup wrote:
Son planted a heap of sweat peas they have spread all over a garden
fence and are a riot of colour. Thing is they seem to be positively
infested by thousands of Hoverflies. Can an infestation like this
damage sweet peas (their is a Rose in the same ground) or will they die
of when the sweet peas do?
Found some small caterpillar/maggot things on leaves do not know if
they are Hoverfly larvae or from cabbage whites so sprayed with "bug
off" and the caterpillar/maggots seem to have died of but this spraying
doesn't seem to have affected the adults either in numbers or proximity
to these sweetpeas.

Thanks all. So just leave these flies be. The caterpillar/maggot
things seemed to be eating the green of the leaves which was incredibly
unsightly (I have no idea if this was actually damaging the plant(s)).
Can remember from previous years (well last year) that there is an
ant colony 'near by' as I seem to remember them crawling about stems
about all I can remember about some ants (don't know if these are the
same species) is that they 'farm' aphids to 'milk' them. Could the
plants be collateral damage in a war between the ants and the hoverflies
or am I overthinking this whole thing?

Certainly getting to know a lot more about the 'minibeasts' in gardens.
Did you know that slaters/woodlice were cousins to prawns (they have
gills which is part of the reason they like it moist)and can in extremis
(survival situation) be eaten. Clipshears/earwigs are carnivorous and
the devil's coach horse (which looks a bit like a giant
earwig/clipshear) is covered in a yuckky tasting, to birds
etc,(poisonous?) coating.