Hoverflies

[JohnC6]

I was wondering if anyone had a possible explanation for this.I have Googled it but no answer.

I was awoken at 6.10 this morning by very heavy rain The overnight temperature was 21C so the bedroom windows were open which is why I heard the rain. It was still dark. I went to the bathroom and put the light on at which point several hoverflies started buzzing around . Others were sitting on the walls ,the ceiling, the mirror and the glass door and the glass screen and door of the shower. I counted 27. One or two flew at me and hit my head. I know they don't sting so I wasn't concerned. They weren't there at 11.30 the previous evening. The bathroom window is oblong and wasn't open that much..about 3". What could have induced so many into the bathroom ? The very heavy rain ? Having said that they may have been there all night. There was no light on upstairs so they weren't drawn in by a light as a moth might be so how did they find the window ? It's white PVC so maybe they'd see it. Why were't they in their nests at night ?

So...I opened the window fully and waited a few minutes hoping they'd go out. They didn't. I got a tumbler and placed it over each one and as soon as it crawled half-way down the glass I withdrew it and clamped my hand over the top and reached out of the window to release it. I have to say I was a bit worried I'd drop the tumbler as I reached out of the window and shook it to get the hoverfly out. Two of them flew straight back in It took me 20 minutes to get each one out of the window as dawn broke. After Googling I found out they don't fly in the dark. I hope they were ok because I also found out that they have very short lives..up to 12 days.. so they would't want to be spending a lot of their time in our bathroom By the way, at 7.15 my wife went downstairs to the kitchen to get a cuppa and told me that there were two on the PVC windowsill. I just opened the window and shoo'd them out. Maybe they have a nest nearby.

 

[Jannyfox]

Are you sure they were hover flies not cluster flies?
I'd never heard of cluster flies btw. I came across them just now while reading up on something completely different..........

 

[Cobra]

Are you sure they were hover flies not cluster flies?

My money is on the latter also.

I'd never heard of cluster flies btw.

They are a real PITA if you get them over wintering in your loft.
They wake up on warm sunny days, and drop down through light fittings or any other small gap, in their 100's,
and head for the nearest light source ie windows.

 

[Box Brownie]

I too had not heard of cluster flies.

Hopefully @JohnC6 can post a picture or two, to identify the ones he has encountered?

 

[JohnC6]

Thanks all for your interest. I didn't think to take a photo,Laurence.....not at 6.15am...lol.

So.I haven't heard of clusters flies,either. I've done a Google and they look like fat flies. Definitely not them. So..I Googled for photos of the hoverfly. First few..no Then.. I came across this website below and it tells me they have illustrated only 12 species. Only 12 ?.. How many species of them are there, then ? Back to Google. Amazingly, 280 in the UK and in an average suburban garden 40 are commonly found.

The ones in the bathroom were "Marmalade Hoverflies". We live and learn,as they say.

It was the same as the header photo and the third one down ..Episyrphus balteatus https://www.discoverwildlife.com/how-to/identify-wildlife/how-to-identify-hoverflies/

 

[Box Brownie]

Thanks all for your interest. I didn't think to take a photo,Laurence.....not at 6.15am...lol.

So.I haven't heard of clusters flies,either. I've done a Google and they look like fat flies. Definitely not them. So..I Googled for photos of the hoverfly. First few..no Then.. I came across this website below and it tells me they have illustrated only 12 species. Only 12 ?.. How many species of them are there, then ? Back to Google. Amazingly, 280 in the UK and in an average suburban garden 40 are commonly found.

The ones in the bathroom were "Marmalade Hoverflies". We live and learn,as they say.

It was the same as the header photo and the third one down ..Episyrphus balteatus https://www.discoverwildlife.com/how-to/identify-wildlife/how-to-identify-hoverflies/

More interesting insect facts as we have over 267 bee species in the UK why not 280 Hover Fly species........the natural world continues to delight & surprise in equal measure.

Now, the question still remains......why did you get so many in the house ?

 

[Cobra]

I've done a Google and they look like fat flies.

AKA cluster flies

 

[JohnC6]

More interesting insect facts as we have over 267 bee species in the UK why not 280 Hover Fly species........the natural world continues to delight & surprise in equal measure.

Now, the question still remains......why did you get so many in the house ?

Yes. Why were they there ? No further replies so I think we'll never know.

 

[JohnC6]

AKA cluster flies

I meant more the size of a blue bottle fly. I should have said that rather than a 'fat' fly.

 

[Cobra]

I meant more the size of a blue bottle fly. I should have said that rather than a 'fat' fly.

Is there a chance that there is either something dead in your loft, or a decomposing bird's nest?

 

[JohnC6]

Is there a chance that there is either something dead in your loft, or a decomposing bird's nest?

I was in the attic this morning and no untoward smell. Whilst Googling them I read that they only eat nectar and the marmalade species eats pollen as well.The only way from the attic into the bathroom is through the bathroom vent system ..the fan is up there but I will check that area in the morning because I can't see them..so many, flying in through a window only 3" open unless the leader went in, by chance and the others followed .Having said that,I read that they don't fly in the dark and as they weren't there when we turned in for the night I think the vent might be favourite. Watch this space, as they say.

 

[Cobra]

I was in the attic this morning and no untoward smell.

You were talking about fly's hence mentioning the decomposing smell.
I'm still not convinced they were hoverflies.
Over the years I've dealt with many infestations, crawling and flying, spiders, fly's, ladybirds,
and smaller critters too.

I've never ever known hover flies to swarm, (they are not social creatures), either inside or out.

unless the leader went in, by chance and the others followed .

As above, I doubt that very much. What we need is an image...

Most flying insects, if not all, are attracted to light.
Hence, experience tells me they are clusterflies that were in the loft, came through the light fittings ( or any other small gap around switches etc.)
and congregated by the window looking for a way out.

edit, one last comment, are you 100% sure they weren't wasps? Have you checked for a nest in the loft?

 

[JohnC6]

You were talking about fly's hence mentioning the decomposing smell.
I'm still not convinced they were hoverflies.
Over the years I've dealt with many infestations, crawling and flying, spiders, fly's, ladybirds,
and smaller critters too.

I've never ever known hover flies to swarm, (they are not social creatures), either inside or out.

As above, I doubt that very much. What we need is an image...

Most flying insects, if not all, are attracted to light.
Hence, experience tells me they are clusterflies that were in the loft, came through the light fittings ( or any other small gap around switches etc.)
and congregated by the window looking for a way out.

edit, one last comment, are you 100% sure they weren't wasps? Have you checked for a nest in the loft?

Very busy all day so late getting into the attic. No dead bodies in there and I didn't see a nest but it would be difficult to see one unless it was on a beam. There's not a mm of gap around the fan housing from the bathroom vent .It's quite a large unit in the attic. I checked the side passage below the bathroom window to see if any fell onto the concrete rather than fly away when I launched them out of that window but there were none there.

I did Google the cluster fly when Jan mentioned it as a suspect to see what the cluster fly looks like and it just looks like a regular fly to me.https://www.pestdefence.co.uk/news/what-are-cluster-flies-and-how-do-you-get-rid-of-a-cluster-fly-infestation/ No black/amber stripes like these had. There was buzzing but hoverflies buzz as a defensive mechanism. Wasps ? I don't think they were large enough to be wasps but you say that you've never experienced hoverflies swarming. I've seen many of them at the same time on the small blue Rozanne Geranium flowers flowers on hot days. Whilst in the garden today I kept an eye out for any but none appeared. Re light. There was no light in the bathroom all night.

I'll be much freer tomorrow and the forecast is good so I'll see if I can get a photo of the hoverflies that often sit on the Geranniums.

As I said to Laurence,I didn't think to get a photo at the time as quite often moths end up in there and I didn't think it would become a mystery.

 

[Cobra]

There was no light in the bathroom all night.

But you said, 6am, by that time it light or getting light so what ever is in your house was heading for the light.
ie the window.

I've seen many of them at the same time on the small blue Rozanne Geranium flowers flowers on hot days.

There is a huge difference between a few feeding from the same bush / flower group,
than swarming.
Again, they are not social.

I didn't think it would become a mystery.

I'm done for now, let me know if or when you get inundated, inside with the cluster flies, and I'll tell you how to deal with the problem.
But it's not likely to become a problem for a couple or so months, or if the weather turns suddenly cold, then again in the spring when they wake up.

 

[JohnC6]

But you said, 6am, by that time it light or getting light so what ever is in your house was heading for the light.
ie the window.


There is a huge difference between a few feeding from the same bush / flower group,
than swarming.
Again, they are not social.


I'm done for now, let me know if or when you get inundated, inside with the cluster flies, and I'll tell you how to deal with the problem.
But it's not likely to become a problem for a couple or so months, or if the weather turns suddenly cold, then again in the spring when they wake up.

Re sunrise. It was 0634. I had to put on the bathroom light when I went in there. By the time I'd finished catching them..20 minutes later some light was appearing in the sky.

Re swarming. Can 27 be considered a swarm ? I don't know. I mentioined that I'd seen "many" (not a few)..about 15-20 ..at one time one time on the flowers ..they seem partial to those in particular but you say they are not social. I read this " Hoverflies are generally solitary but have often been observed in high numbers during foraging or short migrations"

Yes, I agree. We can't take this any further but thanks for your input. All a bit frustrating ,really.