My boys are fine unrugged from the end of October to the beginning of March. Midges cannot cope with cold, wet windy weather. If the weather turns unseasonably mild I do pop the rugs back on, that happened last November. A few good frosts usually kills the midges too.
Same as nettle says, when the midges go, so does the sweetitch. Mine is in a breezy field away from water sources and is now at last rug free! Depends on your location and you do need to keep an eye out in warmer spells, but generally you should be in the clear or nearly there now. Fingers crossed we can sqeeze in a few rug free weeks before clipping and cold weather comes.
I'd keep your rugs on until well into October, unless you're sure there are no midges. the itching suggests that there still are. Ours have to have rugs early March to end of Oct.
Mmmm yes you gotta be careful even through the winter if you get a mild day, the blighters will come back!!! I always play safe and if not sure bung sweet itch hoody rug on, better that than have an itchy.
My routine now the winter's coming will be to vastly reduce feeding supplements, mine's having linseed oil & brewers yeast (don't give garlic to a sweet itch); so now I'll just give him a tiny little bit of each thing just to keep it in his system for the winter; then come the end of January I'll start feeding a bit more to get it in his system before the sweet itch season starts proper in March'ish time. My wake-up call is really half term week in the winter term (i.e. mid February) - you can get midges coming then if its mild so that's a good time to be organised by.
During the winter, I'll look around on the horsey websites for cheapy sweet itch hoody rugs in the sales; you try getting either a sweet itch rug OR a winter turnout rug when you need one .....
With sweet itch, you need to be organised BEFORE the problem manifests. If you've got something itching, you've left it too late. Better to be sorted beforehand.
I *think* the belief is that, as sweet-itch is the result of an overactive immune system, because Garlic is believed to boost the immune system it can actually exacerbate the problem.
Mine is still wearing his rug and it will stay on for a couple more weeks yet. I took it off too early last year and he rubbed the top of his tail raw overnight - that was in September