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Macroinvertebrates home

Streams project

 

Otter Creek

These are the ten most common macroinvertebrates identified by the Saint Michael's College team in the summer of 2008 from Otter Creek.  The samples were collected in North Wallingford, Vermont on July 11th, 2008. 

Click on images to zoom in. 

ORDER: Ephemeroptera
FAMILY: Baetidae 
GENUS: Baetis 

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. SMC

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: 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: 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. SMC

 

 

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 scutellum observable in the dorsal view.
SMC

 

ORDER: Diptera
FAMILY: Simuliidae

Simuliidae appear  rather like bowling pins with heads.  We have not identified them past family at this point, but it is in the long-term plan.


© Aquatic Bioassessment Laboratory, California Digital Reference Collection

ORDER: Ephemeroptera
FAMILY: Ephemerellidae
GENUS: Ephemerella

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.

ORDER: Trichoptera
FAMILY: Rhyacophilidae
GENUS: Rhyacophila

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 a terrifying anal claw which has large accessory hooks. SMC

ORDER: Ephemeroptera
FAMILY: Ephemerellidae
GENUS:
Drunella

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.

 

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 CeratopsycheTo 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. SMC

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
This site is supported by Vermont EPSCoR grant from the National Science Foundation (EPS #0701410).
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