On a canoe trip when I was in Boy Scouts we were at Raquette Lake staying on Big Island in June and the black flies were out of control.  So three of us decided to paddle over to the nearby village to buy a can of Raid.  Once we located the Raid in the store it was about $5.  It was the 70’s and between all of us we only had enough to buy a candy bar, so the bugs won and the candy bar melted.