I’m curious to know that when you visited there were the flies and insects a constant bother?
I visited in early June 2003. It was just after the rainy season, before the dry and hot season, and prior to the rush of European tourists.
The flies and insects were not an issue for me because of being there in early June. But you should bring plenty of insect repellant and take the antimalarial pills and yellow fever vaccine as a precaution. Also make sure you are up to date on your tetanus shots.
If you are sensitive to sun burn bring lots of lotion. The sun can be brutal because of the altitude and lack of clouds that time of year.
Thanks.