San Juan River Hatch Guide

San Juan River Monthly Hatch Chart
Insect Jan Feb March April May June July Aug Sep Oct Nov Dec
Baetis Mayfly (blue wing olive-BWO) size 22
Small and Large Midge: Black, Brown, Olive and Gray
Caddis (Especially strong on the lower river)
Terrestrials, Ants and Hoppers
Pale Morning Dun PMD

Comments: A good rule to follow concerning insect hatches on the Juan is midges in the morning, typically as the sun comes up again in the mid morning and as the sun goes down. Baetis and PMDs in the afternoon. Lasting from about 1:00 pm until 3:30.

There is always some insect activity on the Juan with the most prolific periods being late March, April, May, September, October and November.

The carpenter ant fall, which occurs following the first significant rain of the summer WILL BE the BEST dry fly fishing of the season. The ant is a size 8 or 10 and the fish will eat any big black dry. The ant can fall 2 or 3 times during the beginning of the summer monsoon season.