Academics Admission Student Life Athletics About Saint Michael's News & Events

Site codes explained and mapped  (under mapping resources tab)

Macroinvertebrates home

Streams project

 

Beaver Brook (DR_BeavBrk_1524)

These are the ten most common macroinvertebrates found in Beaver Brook samples.

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.


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.

Hexatoma sp. Tipulidae - photo by Wayne Davis USEPA
US EPA

ORDER: Diptera
FAMILY: Tipulidae
GENUS:
Hexatoma

This Tipulidae can be identified by the swollen 7th abdominal segment.

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. SMC

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: 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

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: 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: Diptera
FAMILY: Ceratopogonidae

Members of this family look like very straight Chironomidae. They are very long and thin with a distinct head capsule and no prolegs.  Some in the lab call them 'bamboo sticks with eyes.' SMC

 

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.

 

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).
2008 Saint Michael's College
One Winooski Park, Colchester, Vermont, USA 05439 | 802.654.2000 |
Privacy Policy