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Macroinvertebrates home

Streams project

 

Cold Brook

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

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. The wing pad shape is an obvious characteristic. 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.  Chironomids 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 the philopotamids.

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; however, not all Trichopterans have forked foretrochantins.

Ceratopsyche have a large pair of sclerites underneath the prosternum. Note: the large single sclerite is the prosternal plate. SMC

 

 

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 tails.

ORDER: Plecoptera
FAMILY: Perlidae
 

This stonefly is characterized by the filamentous gills located on the sides of the thorax. Another important feature is the paraglossae and glossae extending different lengths. The occiput has a transverse row of little hairs evenly spaced. NABS

ORDER: Plecoptera
FAMILY: Perlidae
GENUS: Agnetina

The Agnetina has a rounded abdomen that appears to striped. The key defining characteristic is the three ocelli on the dorsum of the head (3 black dots at joint with the prosternum). Like other Plecoptera, it has 2 tails and 2 claws on its tarsi. SMC

This stonefly is characterized by the filamentous gills located in the "armpit". Another important feature is the paraglossae and glossae extending different lengths. The occiput has a transverse row of little hairs evenly spaced. Agnetina has another row of hair on abdominal segment 7 which is spaced evenly across the whole segment.


© NY DEC / Discover Life

ORDER: Plecoptera
FAMILY: Nemouridae
 

Nemouridae may have branched cervical gills. The outer margin the labium, or lower lip, has three notches. Wing pads are divergent, and hind legs, when extended, reach approximately to the end of the abdomen.

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

ORDER: Diptera
FAMILY: Tipulidae
GENUS:
Hexatoma

These tipulids can be identified by their swollen 7th abdominal segment.

ORDER: Diptera
FAMILY: Tipulidae
 

The majority of fly larvae in the Tipulid family were found to be from the genera Antocha and Molophilus.

 

 

ORDER: Coleoptera
FAMILY: Dytiscidae
GENUS: Dytiscus

We found large numbers of small larvae in the Monroe Brook drainage in particular.  Don't let the paired claws and prominent 'tails' tempt you to think 'stonefly'; these tails are far less segmented than Plecoptera tails. The head and jaws are also unlike those of stoneflies. 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

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