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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. 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:
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: 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 cerci (tails).

Commonly encountered genera include Epeorus, Heptagenia, Maccaffertium, and Rhithrogena.

ORDER: Plecoptera
FAMILY: Perlidae
 

This stonefly is characterized by the three pairs of filamentous gills located on the sides of all three thoracic segments. It is distinguished from the family Pteronarcyidae by the absence of gills on the abdominal segments. Often, the thoracic terga are brightly patterned as pictured, though this is not always the case. Another important feature is that the paraglossae and glossae extend different lengths. NABS

Genera commonly encountered in this family include Acroneuria, Agnetina, and Paragnetina. Less commonly, we have found Perlesta.

Very rarely encountered genera include Neoperla and Hansonoperla. If you believe you have found either of these, please send a specimen our way!

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 "armpits". Another important feature is the paraglossae and glossae extending different lengths. The occiput has a transverse row of evenly spaced little hairs. Agnetina has another row of evenly spaced hairs on the posterior edge of abdominal segment 7.


NY DEC / Discover Life

ORDER: Plecoptera
FAMILY: Nemouridae
 

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

Nemouridae can be distinguished from Taeniopterygidae by the absence of coxal gills.

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: Diptera
FAMILY: Tipulidae
 

Like other larvae from the order Diptera, members of the family Tipulidae (crane flies) lack legs. Tipulidae have retracted, difficult-to-see head capsules at one end, and a spiracular disk at the other end. Upon gently cutting the head open,  one can see that the mandibles are not parallel to each other, but rather move against each other.

The genera we've encountered include Antocha, Dicranota, Hexatoma, Limnophila, Molophilus, Pedecia and Tipula.

 

ORDER: Coleoptera
FAMILY: Dytiscidae
GENUS: Dytiscus

Top picture (adult): Adult Dytiscidae have streamlined bodies and hind-legs modified for swimming. They are characterized by the division of the first abdominal segment by the hind coxae, seen here.

Bottom picture (larva): 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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