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Macroinvertebrates home

Streams project


Brewster River

These are the ten most common macroinvertebrates identified from samples from Brewster River.

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: 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: Helicopsychidae

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.

ORDER: Ephemeroptera
FAMILY: Baetidae

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.

ORDER: Ephemeroptera
FAMILY: Ephemerellidae

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: Coleoptera
ILY: Psephenidae

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: 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.

ORDER: Plecoptera
FAMILY: Perlodidae

Stoneflies in the Perlodidae family do not have branching gills from leg bases. When observing their mouthparts, the glossae and paraglossae form a large three-pronged notch, or opening. Hind wing pads are divergent. Cerci, or "tails," are as long or longer than the abdomen.


ORDER: Plecoptera 
FAMILY: Capniidae
GENUS: Capnia

Capnia  stoneflies have hind wing pads that are are broad as they are long. An important distinction of the Capniidae  family is the membranous pleural folds that run down the posterior abdomen segments 1-9. These look like two lines running parallel down the back of the abdomen.

Capnia are distinguished by femurs and tibia of forelegs with less than 20 fine hairs and no dorsal femoral fringe hairs.

ORDER: Ephemeroptera
ILY: Heptageniidae

This is the only Heptageniidae genus present in this area with two tails!


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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