Use generic Desitin (baby rash cream/zinc oxide) on the bare areas to keep the flies from causing further irritation. Petroleum jelly works too. Buy generic at Walmart or Dollar General. Way cheaper than Swat and no fly repellent necessary. Just the tackiness will keep the bugs off. Both are kind to the skin but the diaper rash cream will protect against sun burn too.
Yes true “summer sores” are caused by fly larvae (worms) but here in the South where gnats can be so bad, they can turn any small knick or cut into an over-granulating mess. The trick is to keep them away in the first place and treat the under-lying wound. I find that Granulex spray is wonderful for this. Keeps the wound bed healthy and from over-granulating and is tacky enough that it keeps the bugs away too. If it’s not overgranulating, slather on the diaper rash cream or vasline and you’re good. Corona is great stuff too but more expensive. I no longer buy Swat as the above works great and without the chemicals.
