Spray yourselves with "Skin So Soft" from Avon (yes, the door to door cosmetics company). It's one of the most effective biting insect repellents.

I find if I garden after 5pm I am more likely to get badly bitten, also if I wear perfume or get very sweaty it seems to be worse.

I haven't had a chance to try Skin So Soft--single men don't attract much attention from Avon ladies--but I have found cedar oil products to be very effective, especially as garden sprays. If you can find where they are breeding, see if you can get permission to apply granular or "doughnut" form organic mosquito killer. The active ingredient is a bacteria (Bacillus thuringiensis israelensis) which only kills larvae of the fly-gnat-mosquito-midge family.

I've just bought a vat of Avon SSS off ebay - 3 bottles for under a tenner.
I got bitten twice last night on my lower calf, little bugger must have got up the inside of my jeans - 3 bites all the size of £2 coins, the bites will bruise and linger for months. Midgies love me :( :( :(
See how they like SSS though ha ha!!!

The army uses skin so soft and vaseline around the ankles.

I found out that the army uses Skin So Soft too Jiffy! Like Drc726, I get bitten in the evening, or late afternoon in winter, and like Donna, I get big, nasty bites. Ouch! Sorry to hear that Donna.

If you sit outside in the evening a burner filled with citronella oil should help discourage them too.