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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Ventral view of a Hydropsyche (Hydropsychidae) (Spotted Sedge) Caddisfly Larva from the Yakima River in Washington
With a bit of help from the microscope, this specimen keys clearly and unsurprisingly to Hydropsyche.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Shillington, Pa

Posts: 2
Billq on Aug 2, 2009August 2nd, 2009, 2:00 pm EDT
Hello, I am new to the entomology of aquatic insects. I do enjoy spending time on this site learning about the things I am fishing with. I am confused by the terms used for nymph and larvae. It seems people use the words interchangeably as if they are the same thing. Is this the case? If you take a look at
they show a yellow caddis larvae and the little green rock worm they call a caddis nymph. Thank you for your help.
Grants Pass, OR

Posts: 302
Creno on Aug 2, 2009August 2nd, 2009, 3:22 pm EDT
in general, entomologists in the US use nymph for the non-egg immature stages of hemimetabolous insects. Larvae are the feeding, non-egg immature stages of holometabolous. Stoneflies have eggs, nymphs, and adults (hemimetabolous). Caddisflies have eggs, larvae, pupae and adults (holometabolous). You will still see them both used inconsistently in the fishing literature. And you will often see larva used by entomologists for immature hemimetabolous insects in other countries.
Pleasant Gap, PA

Posts: 1197
Shawnny3 on Aug 6, 2009August 6th, 2009, 3:46 am EDT
I'm certainly no entomologist, but the distinction easiest for me to remember between these is that the insects that go through a larval stage undergo complete metamorphosis in becoming adults, and those that go through a nymphal stage undergo incomplete metamorphosis. As a fisherman this means to me that nymphs generally look like the adults of that species, whereas larva look way different from the corresponding adults. Even more crudely speaking, the more insect-looking ones are nymphs and the more wormy looking ones are larva.

I'm sure there are lots of entomological shortcomings in my assessment, but that's how I think of them from a flyfishing standpoint.

Jewelry-Quality Artistic Salmon Flies, by Shawn Davis
Martinlf's profile picture
Palmyra PA

Posts: 3047
Martinlf on Aug 6, 2009August 6th, 2009, 2:57 pm EDT
So, Shawn, most of my nymph imitations are actually larvae imitations. :)
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
Grants Pass, OR

Posts: 302
Creno on Aug 6, 2009August 6th, 2009, 4:58 pm EDT
And all my flies look like worms :)
Shillington, Pa

Posts: 2
Billq on Aug 12, 2009August 12th, 2009, 2:35 am EDT
thank you so much for your replies.
Posts: 1
Cassias on Oct 30, 2018October 30th, 2018, 11:29 am EDT
wow this was a long time ago

do you know what fortnite is?
Wbranch's profile picture
York & Starlight PA

Posts: 2635
Wbranch on Nov 5, 2018November 5th, 2018, 3:42 am EST
do you know what fortnite is?

Yes, I know what it is, why did you ask?

Catskill fly fisher for fifty-five years.

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