One wasp got its revenge by hiding in my car and biting me good while I was doing 60mph. I live in the foot hills of the Rockies in Southern Colorado. There are about 20-25 hummers now. Their population doubles in July after they have their chicks. Although the feeder is emptied fast, I use a strong sugar solution of 2 cups of sugar to 4 cups of water, keeps it from fermenting too fast while it's hanging in the sunshine most of the day. Most ppl I talk to use a solution of 1:4.