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Macroinvertebrates home

Streams project

 

French Hill Brook

These are the ten most common macroinvertebrates identified from samples from French Hill Brook.

Click on images to zoom in. 


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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: Plecoptera 
FAMILY: Capniidae
GENUS: Nemocapnia

Capniidae 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.

There are about 15 cercal (or "tail") segments on Nemocapnia stoneflies. There are multiple long, fine hairs on these segments, forming a "vertical fringe," which are absent on the basal 5 or 6 segments (closest to the abdomen).

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: Philopotamidae

GENUS: Chimarra

Chimarra are distinguished from the other Philopotamidae by a prominent asymmetrical notch in the frontoclypeus as well as a prominent process on the femora which bears a single hair (seta). SMC

ORDER: Ephemeroptera
FAMILY: Heptageniidae
GENUS:
Heptagenia

Heptagenia are easily characterized by their flat head. The claws have just one basal tooth and no denticles (serrated edges).  The gill on abdominal segment 7 has multiple fibrils at is base (thread-like structures) and has a single tooth on its claws but is smooth otherwise.  Gills on segment 7 are similar to those on all other segments, but may be smaller in size.

PHYLUM: Annelida
CLASS: Oligochaeta

Aquatic earthworms lack legs and are characterized by having 20 or more segments. Unlike leeches, they lack a suction disk.


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: 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: Philopotamidae

Philopotomidae are net-spinning filtering collectors.  A casual observer might sort them with Chironomidae, but a close look reveals six jointed legs.  The faint white 'T' shaped labrum extending from the front of the head past the mandibles is diagnostic for the family (it is sometimes withdrawn and hard to see). The asymmetrical notch gets us to genus; common genera include Dolophilodes, Wormaldia, and Chimarra. SMC

ORDER: Ephemeroptera 
FAMILY: Leptophlebiidae

Leptophlebiidae are characterized by a somewhat flattened body and forked elongate gills. SMC

Commonly found genera include Habrophlebia and Paraleptophlebia.

 

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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