Cecidomyiidae
Julia Witherspoon
Posts: 12
Hello experts
We have a problem that no-one seems to be able to help us with so I am turning to gardeners instead of pest controllers. Neither myself or my partner are keen gardeners and I have joined this forum to try and get some help and advice.
We have an infestation of gall midges in our home. A local pest controller, and a little later Rentokill, both sent them off for separate analysis as neither we nor either of them had any idea what they were from looking at the flies and the result from both tests (at least we absolutely do know therefore what they are!) is Cecidomyiidae or gall midges.
It doesn`t appear necessarily as if they are breeding in the house (although we cannot be absolutely certain) as the first inspector looked through the house from top to bottom (including the kick boards in the kitchen where food could be stuck and rotting) and we only have a few plants in the house which the midges don`t go anywhere near. They think they are coming in from outside, possibly through the gap between the front door and it`s frame and best guess is that they are likely to be living and breeding in bark we bought and laid about eight months ago (similar time to the start of the flies in the house) all around our front drive way.
However, twice now, I have taped up the front door completely from the inside for a whole day and this has made absolutely no difference at all to the numbers in the house that day. They seem to literally appear from no-where (some are tiny – babies? and others are a bit larger – adults?) and therefore we can’t be sure they aren’t breeding in the house.
There are less of them weirdly when the windows are open (which they are more often now, now that it’s warmer) so they are either breeding in the house and flying out of the windows or not coming into the house when the windows are open (!!). But they continue to be in the house all the time and we are starting to go slightly demented. By the way, there is no visible infestation of flies in the bark, ie, we can’t see thousands of them flying around above the bark all the time although obviously there are a few around. Equally the ‘infestation’ in the house implies there are also hundreds of them flying around all the time but, to be honest, apart from the odd one flying around our heads, they seems to magically appear on the windows, ceiling and cills at the front of the house, where there are probably 100 per day. Sorry for waffling on but I am trying to give as much info as possible in case someone has ever had a similar problem or is particularly familiar with the habits of these ruddy things!
They either die in the base of those swirly long-life light bulbs, in the uplighters or – mostly - on the front of the house window cills where the light is brighter (although a small number do die on every cill in the house). We have tried twice spraying the bark with liquid insecticide from the garden centre but it hasn`t worked (well it didn`t kill the eggs anyway so they continue to breed). The person who tested the flies sent from the first inspector said `.... the application of a residual synthetic pyrethroid insecticide should prove effective`. This hasn`t worked although perhaps he assumed they were on the plants in our garden. This original pest control company aren`t interested in helping us any further and suggested we took up all the bark and got rid of it. We are reluctant to do this unless all else fails (as we cannot be sure they came/come from there and it was expensive) and am sure there must be a way of eradicating these flies once and for all without doing that.
Posts
The second company we called, Rentokill, didn’t even bother doing a survey. They just took some flies away assuming the first people had got it wrong. They hadn’t and this was the reply from their tester:
These are a species of Gall Midge - Cecidomiidae. They are usually fairly small in size -up to 8 mm., wing length 15 mm. They are not a domestic pest and are casual intruders / nuisances. Treat the external areas with a residual wettable powder insecticide after risk assessment. There is not much else you can do with these small insects. You could look at screens on windows also. Internally use an oil based insecticide such as Insectaban or similar to window frames.
On reading this, I have just noticed the sizes he mentions above – up to 8 mm, wing length 15 mm – they are no-where near this size. Our flies are minute. The tiniest ones are like dots with wings and the larger ones are more like 2 mm in length. Odd.
We have only just got this assessment and haven’t tried to do any of this yet. However, we still feel that in order to treat this pest, we need to know once and for all where they are coming from. It isn’t obvious they are coming from the bark inside the house but nor is it obviously they are breeding somewhere in the house.
Can anyone offer any advice? We would be very grateful indeed. If everyone says they must be in the bark, there is no other answer, then we will have to take up the bark but we’d really like to be able to get rid of them without doing this. Rentokill will not treat it themselves as ‘they can’t be sure what else may be harbouring in this area’. So much for being the UK’s largest pest controller.
Thank you for reading this lengthy post. Help!
Julia
Thank you so much for your reply. No we don't and none of our neighbours are having the same problem. The bark does sit on some old soil which we dug up as much as possible before laying the bark. But we had no problems when the soil was there with nothing on top of it. Nothing else has changed in the front driveway area and we have no plants at all (I am embarrassed to say this on a gardening forum!). Do you think if the bark had been been stored somewhere moist or become moist, or been stored near some specific plants before it was delivered to us, it could have had midges inside which then inhabited the soil? Or do they need actual plants to breed? The first inspector said the flies could be breeding in a damp, moist area although this admittedly was before anyone knew what kind of flies they were. If they really can't be in or beneath the bark/soil, I am totally at a loss as to where they are coming from. It sound like you think they can't be breeding anywhere in the house then? That would be something positive! Julia
Thanks for that and for an idea no-one else has thought of in the whole time we have been trying to deal with this, which is amazing seeing as it is such an obvious thing to try now someone has suggested it!
Thank you Pansyface, definitely worth a try particularly in light of no other brilliant suggestions!
Julia
I know you said they don't seem to be around your houseplants but they do sound like fungus gnats (Sciarid flies.) As a test, put all of your houseplants outside for a few days and see if the flies disappear from inside the house. The mismatch in size of the flies that you mentioned makes me think the pest control company may have misidentified them.
I was going to say the same as Bob. Do they have a weak, irregular flight? I would check your pot plants, have a poke about in the compost to see if you can see small maggots, a few mm long, they like damp compost, and feed on the roots. If so they can be controlled with Pyrethrin powder on the compost surface, but it'll take quite a few weeks to be sure, they breed very rapidly. It only take a few to start the whole cycle going.
Sciaridae the black fungus gnats (a different bunch of Sciaroidea from the gall gnats) were my first hunch when I started reading your OP but they are quite obvious in appearance and location, so if they aren't near houseplants or houseplant growing media then it may not be them.
It's probably not a good idea spraying any more good money and not-so-good chemicals around until you have identified the source.
Stick a cloche, bell jar, cut off bottle with some flypaper within it over the top of the bark and on top of a houseplant pot and see what you trap in both.
You could situate any houseplants elsewhere and see if their distribution changes.
Regarding the species.Are their wings dark? Any bites? When do they fly?
Regarding the source Is your place humid? Any houseplant pathologies? Are your guttering, downpipes and site drainage ok? Are airbricks clear and above the ground?
Midges, gnats and mosquitoes flying about the house isn't unheard of. I just tolerate them (concentrating on moths) and use flypaper near plant pots for the fungus gnats, specifically. The flypaper soon gets covered.
There's probably an entomological key somewhere.
Hi everyone
I am so sorry, I haven't seen all your brilliant replies as I hadn't received any more notification emails since pansyface that anyone else had posted.
I really appreciate your feedback. These flies have been sent off by two separate pest controllers with the same analysis so I would think it was accurate even if the sizing was a bit odd. I don't know however if they were sent off to the same place!
Re our house plants, we have one small plant and two Orchids and that is all (hopeless!). I am loathe to move one of the Orchids as it currently has about 40 flowers so clearly loves its location on the kitchen window cill and I'd hate to risk killing the flowers off. These are very different from house plants but we will definitely try and move the one houseplant we do have and see if that happens to make any difference.
LeifUK, they do have weak flight indeed. They congregate on their favourite window cills and fly/hover and crawl around there until they die. There are always dead and half dead ones lying there.
So it seems they may be in the bark and living on beetles. What a horrible thought! Thanks Frank for that trap idea, I think we will definitely try that above the bark before doing what pansyface suggested and covering it completely. Their wings are like normal fly wings, they don't bite at all and once I've hoovered them up off the cills each evening there are hardly any there the next morning so they seem to come alive during the day! I suppose if they are coming in or flying around at night (we do see the odd one flying around our heads in the evening) they are landing in the lights instead of on the dark cills. Our house is not humid at all and is light, bright and airy. We never get mould on window frames etc. We have checked and cleared drains etc.
Btw experts, we did have blocked drains last Autumn and initially the pest controllers thought they may be drain flies who could smell the drains before we could - which is when they were immediately cleared (March). However again, they go nowhere near the drain covers, the loos, the sinks or basins or anything else like that. We have had friends with drain flies and that's what she said they did!
Thank you for all your superb feedback and suggestions. It is hugely frustrating not being able to identify where they are coming from but we have two great suggestions to test the bark theory and will definitely try both.
Julia
Get youself a magnifier and examine one. The general form should tell you roughly what you have. Photographing something that small will be hard without a macro lens and tripod.