The Madison River is one of the most biologically diverse trout streams in Montana. Home to an abundance of insect species, it is no wonder the river is world-famous for producing high-quality fish and plenty of them. Due to the river’s water quality and natural habitat, it harbors large populations of mayflies, stoneflies, caddis, and more. The Madison River’s hatches are varied and prolific, resulting in large populations of wild trout.
Blue Winged Olives (BWOs)
These mayflies hatch in spring and fall on the Madison River. Beginning in late March and lasting through May, BWOs can hatch on any day. Overcast days may see the strongest emergence, especially on the Lower Madison river. On the Upper Madison BWOs can have equally strong hatches on sunny or overcast days. Spring BWOs range from size 14 to 16 and fall BWOs range in size from 16 to 22.
March Browns on the Madison have increased in recent years, making this hatch noteworthy. Typically hatching in late April to mid-May, these large insects become easy pickings for hungry trout. March Browns on the Madison range in size from 10 to 14, with most being size 12. Both the Upper Madison and Lower Madison can have strong hatches.
The famous Mother’s Day caddis hatch on the Madison can begin in late April, but most years the hatch begins around its namesake. An abundance of caddis species live in the Madison. Attempting to name them all would be cumbersome and mind-blowing. However, most caddis range in size 12 to 20, with sizes 14 and 16 being the most prevalent. The Lower Madison sees the bulk of the Mother’s Day caddis hatch, while the Upper Madison has opportunities for caddis hatches from May through October.
This is the hatch that put the Madison on the map decades ago and it is the hatch that still brings many anglers back to the river. Beginning in mid-June on the Lower Madison and migrating upstream well into July, salmonflies are the largest aquatic insects in the Madison. A salmonfly “hatch” occurs over the course of a few days. Nymphs crawl to bankside structure and remove their outer shell—also known as their shuck. When this occurs an adult insect, complete with legs and wings, emerges. These adults cling to structure until it is time to fly and find a mate. Once airborne males and females will mate, females deposit eggs on the surface of the water, and males will soon die. From migration to egg laying can take as long as three or four days. Weather, sunlight, and streamflows are all factors in the quality of fishing during a salmonfly hatch. Nymphs and adults-dry flies-range in size from 4 to 8.
After salmonflies, golden stoneflies hatch. Beginning in late June and lasting into July, a golden stonefly hatch occurs in the same sequence as a salmonfly hatch, however golden stoneflies are smaller. Ranging in size from 8 to 12, golden stoneflies are equally important to trout as salmonflies, they just don’t have the same celebrity status.
Yellow Sally stoneflies
Often mistaken for caddis or PMDs this small stonefly is a crucial part of a Madison River trout’s diet. On the Madison, both Upper and Lower, Yellow Sally stonefly nymphs become active in early June, with adult insects hatching from mid-June well into early August. The nymphs range in size from 8 to 16, with size 10 and 12 being the most common. Because adult Yellow Sallies have very sporadic flying habits trout rarely key on them, but the nymphs are consumed on a daily basis.
Pale Morning Duns
Pale Morning Duns (PMDs) may be a Madison River guides favorite hatch. Beginning in late June and lasting all through July, the riffle-run-pocket-water nature of the Upper Madison river is ideal habitat for these summer mayflies. The Lower Madison is also home to a healthy population of PMDs, but the river above Ennis and its “50-Mile-Riffle” is known for exceptional hatches of PMDs. Nymphs are available to trout year-round, but during a hatch, the hatching insects are a boon to trout in riffles and runs. Most PMDs are size 14 and 16, with size 16 being the most common.
A land-dwelling and distant relative to caddis, spruce moths can be a significant hatch on the river above Ruby Creek. They may emerge as early as mid-July or as late as mid-August, flights of hatching spruce moths cannot be mistaken for anything else. Fluttering near pine trees and bankside bushes, Madison River trout can be overly opportunistic during a strong spruce moth emergence, creating plenty of dry fly fishing opportunities for anglers lucky enough to be in the right place at the right time. Most spruce moths are size 14 or 16.
Terrestrials: Grasshoppers, ants and beetles
As summer moves on, hatches of aquatic insects dwindle. By mid or late July grasshoppers, ants and beetles are a common occurrence and these land-dwelling insects become easy prey for the Madison’s hungry trout. Grasshoppers may seem the most appealing choice, but many Madison trout may forego a ‘hopper and choose a well-presented ant or beetle. A variety of sizes can be successful, but in recent years smaller ‘hoppers in sizes 14 and 16 are more popular than larger sizes and black and brown ants and beetles in size 16 and 18 are the preferred choice.