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> > Caddis larvae vs Mayfly nymph:whats the major difference?

AdirmanApril 15th, 2013, 7:43 pm
Monticello, NY

Posts: 504

Im sure that based on my posts title, you probably realize Im no expert entomologist! Considering this, I was hoping that someone might explain what the major difference is between a mayfly "nymph" and a caddis larva? I know that the mayfly does not go through a pupal stage like the caddis to undergo metamorphosis but beyond that, are there some other clear-cut differences that dictate the distinct designation of 1 as nymph and the other as larvae?

Thank you for your patience,


P.S. Anyone recommend a good hardcore mayfly/caddis entomology book that is more descriptive with morphology/physiological characteris tics?
EntomanApril 15th, 2013, 8:43 pm
Northern CA & ID

Posts: 2604
Hi Adir -

Technically both are larvae. Nymph is a name also in the taxonomic lexicon to define larvae of an hemimetabolous insect whose metamorphosis is incomplete or simple, lacking a pupal stage. Mayflies, stoneflies, damselflies, and dragonflies are aquatic examples of nymphs important to us anglers. To differentiate the post-embryonic immature stages of holometabolous insects like caddis and midges, larva and pupa are the names used.

Hemimetabolous larvae (Nymphs) bear close resemblance to the adult stage.
Holometabolous larvae often appear to be more worm than insect and don't look like the adults at all...

Best books? The good ones like McCafferty's Aquatic Entomology: An Anglers Guide or the even greater detailed Merritt's Aquatic Insects of North America are very expensive. Does anybody know of an eastern equivalent to Hafele/Hughes Western Hatches? It covers the important orders fairly well. Most angler entomology books only cover a single order. I think you can get one fairly cheap (comparatively) at Amazon.
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
DayTripperApril 15th, 2013, 8:53 pm
Northern MI

Posts: 70
I recently picked up Aquatic Entomology on Amazon for like $30 plus shipping. Got my eye on the 2008 version of Merritt's book...

Mayfly nymphs always have two or three tails, caddis larva do not have any tails. Check out some of the photos of each on this website. Once you've looked at a few examples of both, its pretty easy to distinguish one from the other.
CrepuscularApril 16th, 2013, 9:49 am
Boiling Springs, PA

Posts: 923
If you are going to delve into to it go with Merritt and Cummins.
AdirmanApril 16th, 2013, 4:56 pm
Monticello, NY

Posts: 504

As always, an excellent and most informative post thank you! And thanks to all for the book advice!!
EntomanApril 16th, 2013, 6:21 pm
Northern CA & ID

Posts: 2604
My pleasure, Adirman. If there is no eastern equivalent, that Hafele book I mentioned will still be very helpful and much more affordable. The fancy ones aren't about your local hatches, either.
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
SayfuApril 17th, 2013, 9:01 am
Posts: 560
Next Tues it looks like I will be emerging my Grannoms. Got to have a couple of twists of my starling hackle behind the head of my emerging pupas.
Tied up some of Lawson's Partridge wing spent caddis as well. Grannoms are coming off on the Henry's Fork.

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