Insects and other foods the trout may be eating:
1. Blue-winged Olives - mostly Little BWO - Isolated hatches
2. Giant Black Stoneflies - starting any day, nymphs active
3. Hendricksons - hatching
4. Cinnamon Caddis - Mostly Abrams Creek
5  Light Cahills - Starting any day
6. Midges - hatching in isolated locations
7. Little Short-horned Sedges - should hatch randomly for 2-3 months
8. American March Browns - hatching
9. Streamers - matching sculpin, baitfish and small crawfish
10. Little Yellow Stoneflies - starting any day, nymphs active
11. Eastern Green Drakes - starting any day Abrams Creek

Giant Black Stoneflies
Notice Recent Changes in hatches and flies you Need:
Giant Stonellies are those that make up the Pteronarcella family, one of nine
families that make up all stoneflies. The giant black stoneflies are plentiful in
all of the streams in the park. The
Pteronarcys dorsata is the most common species
in the park's streams. They are subject to start hatching any day now.

These are huge nymphs that live for 3 or 4 years. Trout can be taken on imitations
of the large nymphs during the day during the hatch period, even though the Giant
Stoneflies hatch during the evenings. The reason for that is the big stonefly
nymphs come out from under the rocks and begin their short migration to the banks
to hatch. During this time it is easy for the trout to acquire them. Like all stoneflies,
they crawl out of the water to hatch. They do hatch on some of the rocks that come
out of the water as well as the banks. You will see their large shucks on the rocks
and banks as soon as they start to hatch.

Imitations of the adult stonefles fished during the day are rarely effective. These
giant stoneflies hatch during the night. Imitating the adults is not effective unless
you fish very late in the day or during the night. Fishing at night is against the park
rules. In most of the streams, it would be difficult to do so effectively, even if you
were permitted to fish.

Copyright 2009 James Marsh
It is truly amazing to me at the numbers of
these large stonefly nymphs that exist in the
park's streams. They are very abundant.
You will find them just about anywhere there
is fast water.
You will not see them crawling around on the
bottom of the stream. They live down
between and under the rocks. They do
come out to molt several times during their
long life and they come out at night to feed. I
would guess that they (along with the small
crawfish and sculpin) are a big part of the
diet of large brown trout. The best time to
catch trout on imitations of these nymphs is
during the time they are hatching. The trout
become very aware of the hatch.