last week of sept ...white sock/no see'ems is about all there will be that late u could easying get away wit a little bottle of 100% deet ......I make my own for fishing trip as I don't like the "feeling" of that oily crap ...ALONG with what it does to some nylons !....I buy a good 18/24/32 oz chemical spray bottle that puts out a fine mist pour in the little bottle of deet and fill the balance with.... Isopropyl Alcohol its available in 70% and 99%...go with the 99% every time ...shake and spray it's a fine mist that does the job and it evaporates ...so no feelings of oily/nasty...etc... my .02cents
