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Flies from potting compost?
My OH has several pot plants in the house and since August there have been a lot of small flies which seem to be appearing from them. The potting compost was her usual brand from the DIY/garden shop,
The flies are becoming annoying. Anyone heard of potting compost containing fly eggs or pupae?
Or maybe Spallanzani was wrong and it's spontaneous generation after all?!
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They're about that size or slightly bigger and the shape and colour of houseflies. There are I dont know how many thousand species of fly so we're unlikely to identify them but I'd just like to know (and so would she) whether they're likely to have come from the potting compost. No identifiable leaf litter - or cereal stems - in there.
That's a pissibolity. I'll have a good look with a lens in the morning. Right now it's time I was horizontal.
Right. Upright again, physically if not morally.
There are two types of fly! One is as I've described, probably a muscarid, like a tiny house fly or fruit fly. The other is even tinier, possibly gnat-shaped and more closely hanging around the pots - these may well be fungus gnats or similar. Bit of a challenge for the old digital camera but I'll see what I can do,
Sounds like fungus gnats - hang a sticky strip neaby to catch them and top the compost in the pots with grit to stop the adults laying eggs in the top layer of compost - also keep the compost fairly dry, water from the bottom if possible. That shoud cure the problem.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
This query has cropped several times before. This is what I have said then and have kept on file:
"There are two likely possibilities here. You may have fruit flies. They come from fruit but also live in houseplants. They especially like Yucca plants as they are very sweet. You can dispose of these naturally by filling a glass with vinegar and putting cling film over the top. Punch a small hole in the top of the plastic wrap and the fruit flies will go into the jar. Change the vinegar every week or until they are gone.
More likely, they are "dark-winged fungus gnats” (scientific name Sciaridae). These live in potted plant soil. They can be very hard to get rid of, depending on how many infested pots you've got. Nearly everyone who has potted plants has these flies in their homes but they sometimes become a nuisance.
Re-pot the plant completely with sterilised potting compost and spay the soil with BTi (available as 'Gnatrol' in the garden centre)"
I'm betting on the fungus gnats, myself.
Right, After a fly hunt lasting several minutes, the small game hunter has come up with the following:
Fly 1 (living)
Fly 1 (2.5 copies, deceased)
These are obviously similar to house flies or fruit flies, and about the size of fruit flies - maybe 4mm long
And here's the little one, about 1.5mm at a guess but they wouldn't keep still long enough to be measured...
Fly 2 (living, v active)
This is a little more gnatty, but doesn't have the characteristically shaped abdomen. But then maybe they don't.
Right. Off to the shed. By the time I come back I shall expect a full diagnosis complete with origins, evolutionary history, habits and control measures
Thanks.
tbh I'm just quite keen (or OH is) to get rid of them. Grit. Nearly dry compost. That might deal with the fungus gnats, if such they be, but what about the fruit flies? No rotting fruit or yucca. Will try vinegar trap.
I know my Mum would have just nuked the room or whole house with flea spray but that really isn't an enviromentally friendly option
No - nerve gas has never been my preferred treatment. A fly-swat is much more the thing. Or proper old-fashioned fly-papers.
Vacuum cleaner is the answer. Henry has gobbled up 14 of the larger ones and I have no idea how many of the fungus gnats, if that's what they are. Two or three more days of hunting and we may be on the road to victory.
They'll be providing food for the unknown number of spiders in the bag, no doubt