Lewis Creek

Lewis Creek

Basin:	Champlain
State or Province:	Vermont
Country:	USA
Latitude:	44.276909
Longitude:	-73.183287

This wiki page is for Lewis Creek by Quinlan's covered bridge on Spear Street. 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.

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.

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.

Ectopria

Order: Coleoptera
Family: Psephenidae
Genus: Ectopria

False water pennies are less circular than true water pennies, and come to a blunt point at the back end. They appear to have serrated edges and lack gills.

Another genus encountered in this family is Psephenus.

Psephenus

Order: Coleoptera
Family: Psephenidae
Genus: Psephenus

The true "water penny" is commonly found in the waters sampled. Psephenus has a rounded shape with relatively smooth edge. The false water penny, whose edges are serrated, has a more oval appearance. The gills on the ventral surface are found only in the true water pennies.

Another genus encountered in this family is Ectopria.

Ceratopsyche

Order: Trichoptera
Family: Hydropsychidae
Genus: Ceratopsyche

Ceratopsyche has a forked foretrochantin. The foretrochantin is the projection at the uppermost portion of the foreleg. The leg may need to be pulled away from the body to expose this feature. Ceratopsyche have a large pair of sclerites underneath the prosternum. Note: the large single sclerite is the prosternal plate. Biologists have gone back and forth between lumping this genus into Hydropsyche and splitting it back out. ITIS currently lists it as a genus (Feb 2013) but we are aware of a recent paper that lumped it under Hydropsyche.

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.

Antocha

Order: Diptera
Family: Tipulidae
Genus: Antocha

This small dipteran in the cranefly family is quite common. It is distinguished from most other dipterans we found by the 'creeping welts' that appear as prominent dark stripes along the abdomen. The dark head is usually partly exposed; however, it can be pulled back into the thoracic cavity during preservation.

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-

Optioservus

Order: Coleoptera
Family: Elmidae
Genus: Optioservus

The larvae of Optioservus have open coxae, as determined by the straight definition between segments on the ventral side of the pronotum.

The adult Optioservus have a compact appearance, especially the head and thorax. There are also dorsal ridges and a characteristic diamond-shaped sutellum observable in the dorsal view.

Images of the straight definition between segments, the dorsal ridgesand the diamond-shaped scutellum.

Isonychia

Order: Ephemeroptera
Family: Isonychiidae
Genus: Isonychia

Common name: The Dun Variant
Tied fly: Flick's Dun Variant

This mayfly has unique long hairs on its forelegs as the main distinguishing characteristic (allowing anyone keying to move through quickly). Carefully observe the limbs because such hair can be matted down and therefore hidden in preserved wet specimens. The body of Isonychia is slim and "minnow-like" when observed dorsally. In specimens we collected, they were commonly brown and substantial in length and width as compared to the very common Baetidae.

Even when individuals are immature, closer inspection can reveal the setae on the forelegs.

Image of the long hair on its forelegs.

Pteronarcyidae

Order: Plecoptera
Family: Pteronarcyidae

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.

Maccaffertium

Order: Ephemeroptera
Family: Heptageniidae
Genus: Maccaffertium

Common name: The March Brown
Tied fly: March Brown

This genus of Heptageniidae is distinguished by its gills on the seventh abdominal segment, which are reduced to slender filaments. Gills on segments 1-6 are truncated.

Images of the slender filaments, and the truncated gills.

Cheumatopsyche

Order: Trichoptera
Family: Hydropsychidae
Genus: Cheumatopsyche

Cheumatopsyche has a forked foretrochantin (as does Ceratopsyche). The foretrochantin is the projection at the uppermost portion of the front leg closest to the head. The leg may need to be pulled away from the body to expose this feature. Cheumatopsyche have a small or inconspicuous pair of sclerites under the prosternal plate that are difficult to see. Contrast that with the larger pair of sclerites found on Ceratopsyche. To access sclerites, it's best to gently pull the pronotum and mesonotum in opposite directions. Note: the large single sclerite is the prosternal plate. Cheumatopsyche have only 2 types of hair on the abdomen: long thin plain hairs and thicker club hairs, which are narrow close to the body and widen out at the distal end. Paired sclerites on the ninth abdominal segment are notched.

Hydropsyche

Order: Trichoptera
Family: Hydropsychidae
Genus: Hydropsyche

Common name: spotted caddis
Tied fly: dark cahill

Hydropsyche are net-spinning caddisflies and share most characteristics with other members of the Hydropsychidae, including the Ceratopsyche. Hydropsyche are distinguished from Ceratopsyche by the presence of scale hairs and minute spines on the three most posterior abdominal segments.

More information on the Ceratopsyche can be found here. Image of the sclerites in the intersegmental folds.

Baetidae

Order: Ephemeroptera
Family: Baetidae

Common name: Small minnow mayfly
Tied fly: Tiny blue-winged olive

This mayfly has either two or three cerci ("tails") and a unique head shape. Its gills are oval shaped and insert dorsally. Commonly encountered genera include Acerpenna, Baetis and Pseudocloeon.

More information on the genera:

Acerpenna

Baetis

Pseudocloeon

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.

Serratella

Order: Ephemeroptera
Family: Ephemerellidae
Genus: Serratella

Serratella's distinguishing feature is the set of paired tubercles on the dorsum of its abdomen.

Click her to view the paired tubercles.

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.

Ancylidae

Order: Basommatophora
Family: Ancylidae

Members of the family Ancylidae belong in the class of Gastropoda. As Pulmonate snails, these members breathe using lung-like structures but can also use a gill-like structure called a pseudobranch to extract oxygen from water. Their shallow conical shells look like those of miniature limpets.

More information on the class of Gastropoda.

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:

Siphlonuridae

Order: Ephemeroptera
Family: Siphlonuridae
Genus: Siphlonurus

Common name: The Gray Drake
Tied fly: Gold-ribbed Hare's Ear

This family has gills on all abdominal segments. The labrum does not have a deep notch, and maxillae do not have pectinate spines. They have posterolateral spines on their last abdominal segment.

Click to view the spines on the last abdominal segment, unlike those found in Baetidae.

Athericidae

Order: Diptera
Family: Athericidae

Common name: water snipe flies

Members of the family Athericidae have wrinkled bodies with prolegs on the ventral side. Their mandibles- which can be seen by carefully cutting the head open- move parallel to each other. On the end of their abdomen there are two lobes fringed with setae. Our collections include just the single genus Atherix.

Image of the two lobes of the abdomen.

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.

Macronychus

Order: Coleoptera
Family: Elmidae
Genus: Macronychus

This genus can be distinguished from the others by its hind coxae: rather than being transverse, they are globular. Also, it is black and its antennae have only seven segments.

Image of the hind coxae.

Dubiraphia

Order: Coleoptera
Family: Elmidae
Genus: Dubiraphia

The larvae of this genus are distinguished by the last abdominal segment, which is very elongated. Adults of this genus usually have prominent longitudinal markings on their elytra and, like adult Optioservus, have a fringe of tomentum on their anterior tibia.

Image of the fringe of tomentum.

Dicranota

Order: Diptera
Family: Tipulidae
Genus: dicranota

Dicranota can be distinguished by the two tails and their comb feet. There are usually 5 pairs of prolegs on the abdomen with combs on them. In addition, the posterior portion of the abdomen often has a slight swelling.

Image of the prolegs.

Ephemerella

Order: Ephemeroptera
Family: Ephemerellidae
Genus: Ephemerella

Common name: The Hendrickson; The Red Quill; The Hendrickson Spinner Fall
Tied fly: Hendrickson; Flick's Red Quill; Lunn's Particular

Mayflies in this genus have long intersegmental setae on their cerci that extend laterally and may or may not have whorls of spines at the end of each segment of their cerci. Their maxillary palps are well-developed.

Image of the intersegmental setae.