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Macroinvertebrates home

Streams project

 

Oak Ledge Park

These are the most common macroinvertebrates identified from samples from Oak Ledge Park, near the shore of Lake Champlain.  We have not systematically sampled other near-shore locations, but would anticipate significant overlap with this list, at least in the main lake.  Please email us if you find common macroinvertebrates that we have not listed.

Click on images to zoom in. 

ORDER: Diptera
FAMILY: Chironomidae

 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 family Philopotamidae.

 


ORDER: Trichoptera
FAMILY: Hydropsychidae

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. Commonly found genera include Cheumatopsyche, Ceratopsyche, and Hydropsyche. Less commonly, we have found Arctopsyche and Potamyia.

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.

 

ORDER: Trichoptera
FAMILY: Helicopsychidae
GENUS:
Helicopsyche

This caddisfly genus has one local species.  It looks rather like a snail but has lots of sand grains covering it's 'shell' which is really a case.  The anal claws have closely-spaced teeth, much like a small comb.

 

CLASS: Bivalvia
FAMILY: Dreisseniidae
GENUS and SPECIES: Dreissena polymorpha

Because zebra mussels are invasive exotic species, it is important to ensure that they are not inadvertently moved to other water bodies.  Follow the most current DEC guidelines on safe practices when dealing with invasive species.  For zebra mussels the guidelines currently (last checked Nov 2009) include drying equipment for at least 5 days prior to using elsewhere.

 

order: Amphipoda
FAMILY: Crangonyctidae

GENUS: Crangonyx

There is only one genus from Crangonyctidae commonly found in the area.  A "scud," or freshwater shrimp, is distinctly flattened side to side. These can be confused with Isopoda, which are dorso-ventrally (top to bottom) flattened .
SMC

 

 

ORDER: Coleoptera
FAM
ILY: Psephenidae
GEN
US:
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. SMC

Another genus encountered in this family is Ectopria.

 

 

ORDER: Coleoptera
FAM
ILY: Psephenidae
GEN
US:
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.

 

ORDER: Trichoptera
FAMILY: Leptoceridae
 

At least two genera from this family are common in the lake.  The species in the genus Nectopsyche that we have found is very long (2.5 cm) and slender.  Oecetis cases from our samples are shaped like cornucopia. 

 


Aquatic Bioassessment Laboratory, California Digital Reference Collection

ORDER: Lepidoptera
FAMILY: Pyralidae

We frequently find aquatic caterpillars in the genus Petrophila at Oakledge.  The larvae are laterally covered with thick fiber-like structures.

 

ORDER: Trichoptera
FAMILY: Uenoidae
GENUS: Neophylax

Neophylax are characterized by having a sclerotized pronotum and mesonotum. a rather stout Trichoptera. The head is scrunched in between the arms, and the anal hooks are connected directly to the bottom of the abdomen. 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.

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-pupaeWe 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. SMC

 

ORDER: Diptera
FAMILY: Tipulidae
GENUS: Antocha

This small Diptera 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.
NABS

 

ORDER: Ephemeroptera
FAM
ILY: Heptageniidae

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, and Rhithrogena.

 

ORDER: Isopoda 
FAMILY: Asellidae
GENUS: Lirceus

These aquatic invertebrates are also known as sowbugs. They are flattened top to bottom.

Be sure not to confuse them with the terrestrial sowbugs that can, on occasion, end up in aquatic samples. Terrestrial species have both shorter antennae and legs. SMC

 

ORDER: Trichoptera
FAMILY: Polycentropodidae
GENUS: Polycentropus

The most common genus we encounter is Polycentropus. These caseless caddisflies frequently have speckled or freckled heads.  The anal proleg typically has a prominent black X, although it can in some specimens appear to be a little faded.  They are common at Oakledge Park in Lake Champlain, where we also find an additional genus in the same family: Nyctiophylax.

 

 
         

The images are not a substitute for keying, but should serve as an aid in identifying common macroinvertebrates in samples.

Feedback - Partner schools: send us specimens not included above.  Taxonomists: click to email: Declan McCabe
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