With a special focus on Mayflies, Caddisflies, and Stoneflies Aquatic Entomology & Benthic Macroinvertebrates

Why are there so many insects around streams, rivers, and lakes? Aquatic insects spend the majority of their lives in water. Hatch in/under water Live for a large percentage of their life under water getting bigger. When they are ready for adulthood they rise/crawl to the surface to molt and begin the adult portion of their life above the surface At this point their primary goal is to reproduce

Why look at invertebrates? An immediate indication of water quality can be seen just by observing what is living in in it. Invertebrates are broken down into 3 taxons: 1) Pollution sensitive 2) Somewhat- sensitive 3) Tolerant What if you find no sensitive organisms in a stream? ** Diversity is key! When fishing they help you understand what insects are present and therefore what the fish may feed on.

Benthic Macroinvertebrates Benthic- Bottom dwelling Macro- large Invertebrate- spineless organism ** Large bottom-dwelling spineless organism Most are found in the substrate or on the bottom of rocks. Scrapers, Shredders Some are climbers- climb up on plant and stems For fishing we will look at when they are below and above water.

Invertebrate Classification Taxonomy- science of naming and classifying organisms Each organism is given a two part name consisting of a Genus(noun) and a species(adjective) Kingdom Phylum Class Order Family Genus Species

Insect Identification Insect identification begins with the Class- Insecta Then is divided into more specific orders. Three important examples are: Mayfly = ephemeroptera Caddisfly = Trichoptera Stonefly = plecoptera A dichotomous key is often used for insect identification This tool uses a list of identifiable characteristics to group organisms into related taxons

Adult Mayfly Note the Sailboat wings

Adult Caddisfly Note the tent wings

Adult Stonefly Note the size and flat wings

Insect Life Cycles Most insect invertebrates found in a stream are in some stage of metamorphosis All insects undergo some type of Metamorphosis (series of life changes from the egg to the adult) Two types- 1) complete 2) incomplete

Complete Metamorphosis Four stages: 1) egg 2) Larva- all insects have the post embryonic larval stage 3) pupal- transitional stage, stationary cocoon or mobile 4) Adult- above water Ex. Butterfly

Incomplete Metamorphosis Has no Pupal stage Larval stage is characterized by a series of molts Periods between molts are called instars Insect is sometimes referred to as a nymph or naiad during the larval stage

Metamorphosis for the beginning fly fisher (Caddis example) Caddis “nymph” Adult Caddis

Mayfly Life Cycle

How do most fly fishers refer to insect life cycles? “Nymph” = Bottom dwelling version “Pupae” = Worm-like stage “Emerger” = Making it’s way to the surface “Adult” = Normal flying version “Spinner” = Laying eggs

What “life cycle stage” should I fish with? It depends on quite a few things What are the fish feeding on Do you like fishing a dry fly or nymph? What is your fly selection? Trout get 90% of their food underneath the surface. Nymphing is more productive!

Invertebrate Sampling Kick net- large net used to sample a 3’x3’ area in a riffle(current in a stream) 1) Place the net in a riffle, weight down the bottom to prevent escaping underneath 2) pick up and rub large rocks, place aside 3) Stir the substrate by kicking thoroughly with your feet Grab net- lower right Most fishers will turn over rocks or run their hands through the bushes to try to locate bugs