Updates from February 7, 2004
Eurylophella (Chocolate Duns) Mayfly Nymph
View 5 PicturesThis nymph is an extremely early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.). Baetidae (Blue-Winged Olives) Mayfly Nymph
View 5 PicturesThis nymph has only two real tails. The third is present, but too short to see in these pictures. It has particularly small gills and indistinct gill veinlets (Veinlet: Short insect wing veins connecting the major longitudinal veins to the wing margin.). Ephemerella invaria (Sulphur Dun) Mayfly Nymph
View 4 PicturesI looked at this small Ephemerella nymph very carefully under a microscope. It as no abdominal tubercles (
A few (not all) of the abdominal tubercles on this
Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.) and 1-banded tibiae (Tibia: A middle segments in the leg of an insect, located between the femur and the tarsus.). I think just a very early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.) invaria nymph. Leucrocuta hebe (Little Yellow Quill) Mayfly Nymph
View 3 PicturesThis is a very early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.). Ephemerella subvaria (Hendrickson) Mayfly Nymph
View 3 PicturesThis is another peculiar brownish Ephemerella. It has double-banded tibiae (Tibia: A middle segments in the leg of an insect, located between the femur and the tarsus.) and prominent black-fringed tubercles (
A few (not all) of the abdominal tubercles on this
Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.). Ephemerella invaria (Sulphur Dun) Mayfly Nymph
View 4 PicturesI looked at this nymph closely under a microscope to ascertain some key features I was wondering about in previous photographs of similar specimens. It definitely does have the fan-tail characteristic of the Ephemerella genus. It also has strongly 2-banded tibiae (Tibia: A middle segments in the leg of an insect, located between the femur and the tarsus.) and definite tiny abdominal tubercles (
A few (not all) of the abdominal tubercles on this
Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.). Eurylophella (Chocolate Duns) Mayfly Nymph
View 3 PicturesLooking at this specimen under a microscope revealed prominent sharp abdominal tubercles (
A few (not all) of the abdominal tubercles on this
Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.). Also, abdominal segment 9 is distinctly longer than abdominal segment 8, meaning this is definitely a Eurylophella nymph. Eurylophella (Chocolate Duns) Mayfly Nymph
View 3 PicturesThis nymph is an extremely early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.). Eurylophella (Chocolate Duns) Mayfly Nymph
View 3 PicturesThis nymph is an extremely early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.). Eurylophella (Chocolate Duns) Mayfly Nymph
View 3 PicturesThis nymph is an extremely early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.). Clitelatta-Oligochaeta (Worms) Worm Adult
View 2 PicturesI know most people know what a worm looks like, but when trying to tie an imitation, the memory is often a poor source of accurate color information, and a picture helps to get the right shade. One thing that surprised me in my sampling is that quite a few worms did turn up. Before I was a fly fisherman, when I used worms for bait, I always thought they were merely a tantalizing morsel and not a regular trout food, but I've since realized that there are quite a few worms that live in the sediment on a stream bottom. Epeorus vitreus (Sulphur) Mayfly Nymph
View 3 PicturesKey features I discerned with a microscope include that the femoral flange is blunt (later note: on nymphs of this size, it's somewhat ambiguous and the femora (Femur: The main segment of an insect's leg close to the body, in between the tibia and the trochanter.) can be damaged in the collection process), the postero-lateral (Lateral: To the side.) spines have a longer anterior (Anterior: Toward the front of an organism's body. The phrase "anterior to" means "in front of."), the first gill is not extended, all gills are tracheated, and the femora (Femur: The main segment of an insect's leg close to the body, in between the tibia and the trochanter.) have a distinctive brown spot on the center while all the other spots are gray. Epeorus vitreus (Sulphur) Mayfly Nymph
View 2 PicturesKey features I discerned with a microscope include that the femoral flange is blunt (again, given the other features and location, I probably misread this one), postero-lateral (Lateral: To the side.) spines with the anterior (Anterior: Toward the front of an organism's body. The phrase "anterior to" means "in front of.") longer, and the first gill is not extended. Baetidae (Blue-Winged Olives) Mayfly Nymph
View 3 PicturesClose examination under a microscope revealed that this Baetid nymph has segment 5 pale, segments 8, 9, and 10 pale but less so, a middle tail almost as long as the outer tails, conspicuous gill veinlets (Veinlet: Short insect wing veins connecting the major longitudinal veins to the wing margin.), no bands on its tails, and pointed, slender 7th gills.
Most recent comments on this post (latest on top)
Comment on this post
You must
log in at the top of the page to post. If you haven't registered yet, it's this easy: