Fly infestation

teddybones

I have noticed an infestation of flies this winter. I know the weather is unseasonably warm but these flies are strange. They are not like house flies, fruit flies or blue bottles. They are like elongated house flies with a furry thorax. They are gross. Every time I open my back door up to twenty or thirty might fly in. They congregate around a terrapin tank I have in the kitchen or the ceiling so are clearly attracted by the light. I checked my yard yesterday just to see if there was anything, like a dead bird or something that might be producing them but nothing. I can't spray insecticides. They seem to die off pretty quickly falling into the terrapins tank (he eats them) but my daughter is horribly freaked out by them. We have never had them before. I guess they have been around for the last 4 weeks. Growing in numbers. They are less when it was the cold spell. Anyone any insight?