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 West Branch Trib A |
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| Stream code: | WR_WBLRTribA_725 |
| Basin: | Winooski River |
| State or Province: | Vermont |
| Country: | USA |
| Latitude: | 44.478746 |
| Longitude: | -72.691399 |
| School: | Stowe High School |
The following are the most common invertebrates collected from this stream site.
Chironomidae
- Order
- Diptera
- Family
- Chironomidae
- Common name
- Nonbiting midge
- Tied fly
- Griffith's Gnat
Midge larvae tend to be the most common macroinvertebrate at our sites. As with other Diptera, there are no true jointed legs. Chironomidae do have a pair of prolegs at each end and preserved individuals tend to curl into a 'C'. Identification past family requires slide-mounted heads. We have seen philopotamid caddisflies misidentified with the chironomids and we suspect that that happens when samples are being sorted from trays. Under a microscope, six prominent legs can be seen on members of the caddisfly family Philopotamidae.
More information on Philopotamidae.
Baetis
- Order
- Ephemeroptera
- Family
- Baetidae
- Genus
- Baetis
- Common name
- The Little Olive
- Tied fly
- Sawyer Pheasant Tail Nymph
This mayfly has three "tails" and a unique head shape. Its gills are oval shaped and insert dorsally. More mature nymphs have long, dark wing pads.
Image of the long, dark wing pads.
Simuliidae
- Order
- Diptera
- Family
- Simuliidae
Simuliidae appear rather like bowling pins with heads. Relatively speaking, we collect few members of this family and have we have not identified them past family at this point.
Click here for a close up image of the heads.
Leuctra
- Order
- Plecoptera
- Family
- Leuctridae
- Genus
- Leuctra
This family of stonefly is fairly slender by stonefly standards. The divergent wing pads are a helpful characteristic. Leuctridae are similar in overall shape to the Capniidae; however, Leuctridae often do not have pleural folds. If they are present, they only extend from abdominal segments 1-7.
Leuctra are recognized by abdominal terga with posterior fringes of short hairs and last few segments with longer hairs.
Image of the divergent wing pads.
Pseudocloeon
- Order
- Ephemeroptera
- Family
- Baetidae
- Genus
- Pseudocloeon
- Tied fly
- Bluewinged Olive
Mayflies in this genus have a distal lobe on their antennal scapes, and the second segment of labial palps has an expanded medial process. Villopores are absent on legs.
Click to see the antennal scapes. The dorsal and ventral views can be seen here.
Glossosomatidae
- Order
- Trichoptera
- Family
- Glossosomatidae
- Common name
- saddlecase caddisfly
Larvae in this family build domed cases made of small rocks, and are often wider at segment 5. The pronotum is covered in dark, sclerotized plates, but there are either
no sclerites on the mesonotum, or the mesonotum is unsclerotized with the exception of a few patches. The anal proleg is broadly joined to segment 9; the anal claw has one or more accessory hooks. The
pronotal excision is small (approximately 1/3 anterolaterally) to accommodate the coxae.
Commonly encountered genera include Glossosoma and Agapetus.
Pteronarcys
- Order
- Plecoptera
- Family
- Pteronarcyidae
- Genus
- Pteronarcys
- Common name
- The Giant Stonefly
- Tied fly
- Kaufmann's Black Stone
Pteronarcyidae have branching gills from the bases of their legs as does
Perlidae. What distinguishes Pteronarcyidae from Perlidae is the presence of gills on the first two abdominal segments. There are only two genera in this family, but the other,
Pteronarcella, is only found in the west/southwest.
Click to see an example of Perlidae or the gills on the first two abdominal segments.
Oligochaeta
- Common name
- aquatic earthworms; black worms
Aquatic earthworms lack legs and are characterized by having 20 or more segments. Unlike leeches, they lack a suction disk. We collect members of two or more orders in this class as small numbers of stream sites and they are rarely numerous. They are more common at pond and lake sites.
Image of the 20 or more segments.
Acerpenna
- Order
- Ephemeroptera
- Family
- Baetidae
- Genus
- Acerpenna
- Common name
- Tiny blue-winged olive
This genus is can be identified by the costal process, or projection, distal to the hind wing pad. Gill 7 is slender and may be pointed at the end. The antennal scape and pedicel have a few scattered setae (hairs).
Image of the antennal scape. A ventral view can be seen here.
Agnetina
- Order
- Plecoptera
- Family
- Perlidae
- Genus
- Agnetina
Agnetina nymphs have cylindrical, striped abdomens. Like other Plecoptera, they have 2 tails and 2 claws on each tarsus. This genus has three black dots (ocelli) on the top of the head. Click to see the
three ocelli on the dorsum of the head (3 black dots at joint with the pronotum). This stonefly is characterized by the
filamentous gills located in the "armpits". Another important feature is the paraglossae and glossae extending different lengths. The
occiput has a transverse row of evenly spaced little hairs.
Agnetina has another row of evenly spaced hairs on the posterior edge of
abdominal segment 7.
Tipulidae
- Order
- Diptera
- Family
- Tipulidae
- Common name
- The Crane Fly
- Tied fly
- Gangle Legs
Like other larvae from the order Diptera, members of the family Tipulidae (crane flies) lack legs. Tipulidae have retracted, difficult-to-see head capsules at one end, and a spiracular disk at the other end. The spiracular disk can sometimes look like a face leading to some confusion about which end is which. Upon gently cutting the head open, one can see that the mandibles are not parallel to each other, but rather move against each other.
The genera we've encountered include Antocha, Dicranota, Hexatoma, Limnophila, Molophilus, Pedecia and Tipula.
Alloperla
- Order
- Plecoptera
- Family
- Chloroperlidae
- Genus
- Alloperla
Chloroperlids stoneflies are quite slender relative to most other stoneflies. The adults are green but this trait does not show up in the nymphs. Chloroperlids from this genus are characterized by a fringe of intrasegmental setae on their cerci.
Image of the intrasegmental setae.
Rhyacophila
- Order
- Trichoptera
- Family
- Rhyacophilidae
- Genus
- Rhyacophila
- Common name
- Green Caddis
- Tied fly
- Henryville Special or Glass Bead Caddis
In our lab,
Rhyacophila is known as the "Michelin Man" due to its large banded body. It has a very obviously checker-patterned head. It also has terrifying anal claws with large accessory hooks.
Links to images that may be useful if you have a magnifying glass or microscope:
Checker-patterned head.
Anal claws with large accessory hooks.
Hydropsychidae
- Order
- Trichoptera (caddisfly)
- Family
- Hydropsychidae
- Common name
- net spinning caddisfly
- Tied fly
- Emergent Sparkle Pupa, Vermont Hare's Ear
This family of net-spinning caddisflies is very abundant at several sites. They are important filtering collectors and are quite common at urban and agricultural sites where particles of organic material can be important food resources. Genus-level identification is possible for mature specimens and we will include the genera we found at your site if possible.
When using the key, some features that are challenging to see are the forked trochantin and the paired sclerites in the folds between segments. Other, more easily seen key features include filamentous gills on the abdominal segments and the sclerotization of the dorsal surfaces of all three thoracic segments. Keep in mind that with smaller or more immature specimens, genus-level ID may not be possible.
Commonly found genera include Cheumatopsyche, Ceratopsyche, and Hydropsyche. Less commonly, we have found Arctopsyche and Potamyia.
Images of the forked trochantin and the paired sclerites.
Limnophila
- Order
- Diptera
- Family
- Tipulidae
- Genus
- Limnophila
This genus of
Tipulidae has a spiracular disk with 4 lobes fringed with long hair. Out of the other end, simple, non-jointed mandible project even when the head is retracted (pictured in the lower left area of the main image). The head, which can be viewed by cutting away the skin, is not extensively sclerotized. Rather, the sclerites are long, slender rods.
Image of the head.
Heptageniidae
- Order
- Ephemeroptera
- Family
- Heptageniidae
- Common name
- flatheaded mayfly
- Tied fly
- Light Cahill, Wingless Pale Evening Dun
This family of mayflies can be characterized by their distinctly flattened heads and striking resemblance of the character 'Jack Skellington' from the movie 'The Nightmare Before Christmas.' This family can either have two or three cerci (tails).
Commonly encountered genera include:
Epeorus
Heptagenia
Maccaffertium
Rhithrogena
Drunella
- Order
- Ephemeroptera
- Family
- Ephemerellidae
- Genus
- Drunella
- Tied fly
- Bluewinged Olive Dun
The mayfly Drunella is distinguished by its large femoral “biceps;” these femora have tubercles on the leading margins. Gills are present on segments 3-7.
Amphinemura
- Order
- Plecoptera
- Family
- Nemouridae
- Genus
- Amphinemura
We rarely encounter this stonefly genus.
Acroneuria
- Order
- Plecoptera
- Family
- Perlidae
- Genus
- Acroneuria
Acroneuria are among the most common Perlid stoneflies that we find. The larvae have a close-set postocular fringe consisting of thick spinules. They have three ocelli, and a yellow m-shaped mark in front of the middle ocellus. The bases of their cerci have thick, silky setae.
The postocular fringe can be seen here. Look in front of the three ocelli for the yellow m-shaped mark. Focus where the cerci meet the body to see the thick, silky setae.
Brachycentrus
- Order
- Trichoptera
- Family
- Brachycentridae
- Genus
- Brachycentrus
- Common name
- The Olive Dun Caddis
- Tied fly
- Deer Hair Caddis
These larvae are typically found with their legs extended out of their case for feeding. The cases are square in cross section and made of plant materials. Brachycentrus has 2 large sclerites on the metanotum. In fresh samples (preserved for less than one week) these organisms often have a pale green tint; live specimens are a more vivid green.
Neophylax
- Order
- Trichoptera
- Family
- Uenoidae
- Genus
- Neophylax
- Common name
- Fool's Caddis
- Tied fly
- Peeping Caddis
Neophylax are characterized by having a sclerotized pronotum and mesonotum. They build a case of coarse sand grains often with a pair of latteral pebbles or "ballast stones". The larvae are rather stout and the head is scrunched in between the limbs. The anal hooks are attached directly to the abdomen and they rarely come out of the case when preserved. On the ventral surface of the abdominal segments, one can see darkened ovals, known as the chloride epithelia. Like the
Limnephilidae, they have a prosternal horn, though it can sometimes be small. Also, they have a dorsal hump and two lateral humps on the first abdominal segment- be careful! Often times, these features can be
squished down or damaged in the sampling process. A larva removed from it's case is shown
here.
The feature that distinguishes Uenoidae from Limnephilidae is the mesonotum: on either side of the midline, the anterior margin is notched.
Because our samples were taken in summer, we found large numbers of Neophylax pre-pupae. We anticipate that there will be fewer present in the streams in late September and many of those sampled will be at the pupal or adult stage. Samples taken in October would tend to have more empty cases.
Stenelmis
- Order
- Coleoptera
- Family
- Elmidae
- Genus
- Stenelmis
The larvae of
Stenelmis, as in
Ordobrevia, have a sternum on the ventral side of the pronotum. The main difference between the two genera is in the antennae the second segment is less than twice as long as the first in
Stenelmis.
The adult Stenelmis has a clear separation between the thorax and abdomen as well as a more distinctly separate head as compared to other genera.
Click here to see pictures of the sternum and
antennae-
Gomphidae
- Order
- Odonata
- Family
- Gomphidae
- Common name
- clubtail dragonflies
Like other Odonata, members of this family have four wingpads. Like members of the sub-order Anisoptera, the abdomen terminates in five points. What distinguishes Gomphidae from Aeshnidae is the fact that Gomphidae has clubbed antennae.
Image of the four wingpads and the abdomen.
More information on Aeshnidae.
West Branch Trib A
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