Blowflies have the sense to make a great fuss about the fact that they've somehow got themselves trapped indoors, and are eternally grateful if you open a window for them that they can actually find their way out of. Although they do seem a little lacking in brain: open a window and they'll fly smack into the closed one next to it, or sit on the glass in the open window wondering where the breeze is coming from. But at least they generally leave when requested. And they plainly have places to go and things to do, if the speed of their departure is anything to go by.
These other little flies, however, have long since outstayed their welcome - though at least they don't make any noise. Finally we made up a mix of vinegar and water to spray at them, because I don't like using normal fly sprays, especially in the kitchen. All that happened was they got wet and carried on swinging back and forth across the room drying themselves. My daughter's comment was that the only way they would die was if they drowned from excess water. This didn't seem to happen.
Last night we resorted to using a proper fly spray. There was a sudden emptiness in the middle of the room after I'd sprayed it at them, and I was sure they'd all been sent to the place where all flies go (not somewhere I'm keen to follow, incidentally). Obviously one or two missed the blast, because this morning I notice that distinct movement out of the corner of my eye. Hopefully however, they'll have the sense to realise that the Summer holidays are over and they need to go back to wherever they came from.
We've moved to Oamaru since I wrote this post. Oamaru is a town about an hour and half's drive from Dunedin, our former home. Here we have an ongoing problem with small flies, and in fact we got a fly net to cover the back door which is where the bulk of them were coming in from. As in Dunedin, the big blowflies, the noisy ones, will happily go out a window if you open it for them. Not the little fellows: they love to hang round making no noise, floating across the room, or landing somewhere you think you can swipe them and then whistling off at great speed...only to linger in the air again once the danger has passed. My wife is not fond of them, and even though we've used fly spray on them, it seems you have to get them dead on for it to have any effect.