A Fly In The Ointment...............

I’ll admit that I like to keep my home nice and warm, and have had the heating turned up again during this recent cold snap, but I hadn’t realised quite how hot it must be until a small mosquito landed on my arm in the lounge yesterday….

No hang on minute,…. it’s not a mosquito, it’s a fruit fly…..No, it’s not a fruit fly,…… it’s a sciarid fly .......Bugger!

The sciarid ( or "sciara") fly looks just like a fruit fly, to all but its own ilk presumably, but is an indoor garden pest. There are several different variations in the sciarid family, and they are often generally referred to as fungus gnats. The above picture makes them look quite scary, but in fact they are very small and midgey. Basically they love warm ,wet soil or compost, where the adults emerge from, and return to, to lay their eggs. These then hatch into tiny, tiny larvae, which feed on the roots and soft parts of seedlings.

A serious outbreak in a greenhouse can decimate tender plants, and it’s a particular nemesis of cacti fanciers apparently. Even a modest infestation can weaken a tray of veg seedlings and transfer the viruses that lead to “damping off”.

A quick inspection of the pots on my window sill unmistakably confirmed where the trouble was, and how I had contracted it.

A week ago I planted some climbing beans, courgette seeds, and spring onions in modules, and had brought them indoors to germinate. Not wanting to waste anything, and trying to be environmentally friendly, I had used up the remains of last year’s potting compost, from a bag in the shed…..Big mistake. ….Always use fresh, unopened compost each year, unless you are going to heat sterilise it first.

The flies had holed up in it over the winter, been smuggled indoors, and had suddenly sprung to life in my sub-tropical kitchen.

There are a couple of things you can do to try and control the problem, if confined to a small area or number of pots.

Firstly, remove any obviously contaminated containers and isolate them in another room where the flies can’t emigrate to other plants. I put the beans and courgettes in the bathroom, and shut the door on them, as they are now sprouting, and I don’t really want to chuck them out. The onions that had not yet germinated all got the heave-ho I’m afraid. I’ll have to start them again later.

Secondly I put down a saucer of cider vinegar in the window, which supposedly lures the adult flies to an appley death…. After going out for the morning however, I returned to find, not the fly encrusted bowl of doom I had hoped for, but merely a house that stinks of vinegar.

I have now replaced it with a saucer of red wine, which whilst being a criminal waste, is at least not offensive to live with, and is supposed to have the same effect.

Now I have to wait a few days for existing adults to die off, before starting my seedlings again in new compost.

The only other problem is that they may have already laid eggs in the soil of rubber plant in the lounge. This is unlikely to hurt the rubber plant, as it is the toughest specimen in the world. (Purely on the basis that I have had it for over 25 years and have not killed it yet.) They could re-emerge to re-infect new pots coming in though, so I’ll have to keep an eye in it.

As they need moisture to survive, I’ll let the plant dry right out (No change there then) before watering it again, and put a layer of sand on the top of all the pots, as this dries faster than compost, and acts a deterrent barrier.

If all of this doesn’t work, I’ll just spray them……. Attempting to be eco-conscious got me into this, so chemicals can get me out!