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Macroinvertebrates home

Streams project

 

Lake Sunrise Outlet (LCC_HubbRv_439)

These are the most common macroinvertebrates identified from samples from the Lake Sunrise outlet in Benson, VT.  We have added common names to this site for use with younger cub-scouts.

Click on images to zoom in. 

Brush-legged mayflies swim like little minnows when caught.  They have low tolerance for pollution, and given that they were the most abundant insect in our samples, it speaks well of the water quality (but don't drink it - I have heard that lots of kids swim upstream :) )

ORDER: Ephemeroptera
FAM
ILY: Isonychiidae
GEN
US: Isonychia

This mayfly has unique long hairs on its forelegs as the main distinguishing characteristic (allowing anyone keying to move through quickly). Carefully observe the limbs because such hair can be matted down and therefore hidden in preserved wet specimens. The body of Isonychia is slim and "minnow-like" when observed dorsally. In specimens we collected, they were commonly brown and substantial in length and width as compared to the very common Baetidae. Some individuals are immature, but upon closer inspection one can see the setae on the forelegs.

Larvae of non-biting midges

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.

Flat-head mayfly.  There are at least 2 types in this stream

ORDER: Ephemeroptera
FAMILY: Heptageniidae
Genus: Maccaffertium
 

This genus of Heptageniidae is distinguished by its gills on the seventh abdominal segment, which are reduced to slender filaments. Gills on segments 1-6 are truncated.

Finger-net caddisfly.  Their nets are usually under rocks.

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

Flat-head mayfly.  There are at least 2 types in this stream.  The Genus Epeorus in unusual among mayflies because it has 2 'tails' but the broad flat head distinguishes it from stoneflies.

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.

Common net-spinner caddisfly (we found 3 types in this stream)

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

Stonefly.  There are at least two types of stonefly at the site.  Stoneflies have two 'tails'.

ORDER: Plecoptera
FAMILY: Leuctridae
GENUS: Leuctra

This family of stonefly is fairly slender by stonefly standards.  The divergent wing pads are a helpful characteristic. Leuctridae  are similar in overall shape to the Capniidae; however, Leuctridae often do not have pleural folds. If they are present, they only extend from abdominal segments 1-7.  Leuctra  are recognized by abdominal terga with posterior fringes of short hairs and last few segments with longer hairs. NABS

Common net-spinner caddisfly (we found 3 types in this stream)

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

 

 

Blackfly larva

ORDER: Diptera
FAMILY: Simuliidae

Simuliidae appear  rather like bowling pins with heads.  We have not identified them past family at this point, but it is in the long-term plan.

Hellgramite or dobsonfly - larger ones can bite

ORDER: Megaloptera
FAMILY: Corydalidae
GENUS: Nigronia

Members of the genus Nigronia share some superficial commonalities with Trichoptera, but on careful inspection one can see the two pairs of anal claws that help place it in the order Megaloptera.  The size of mature larvae is impressive; specimens from other genera exceed 8 cm in length.  The abdominal segments have ribbon-like gills on the lateral portions. The mouth has mandibles that are serrated and used for biting prey.  They can be confused with the more slender whirligig beetle larvae; whirligig larvae also have simpler jaws  SMC

Common net-spinner caddisfly (we found 3 types in this stream)


 

ORDER: Trichoptera
FAMILY: Hydropsychidae
GENUS: Hydropsyche

Hydropsyche share most characteristics with Ceratopsyche, including the sclerites in the intersegmental folds. Hydropsyche are distinguished from Ceratopsyche by the presence of scale hairs and minute spines on the three most posterior abdominal segments. SMC

Free-living caddisfly.  They are typically green when alive.

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

Club-tailed dragonfly.  You may find other dragon flies in this stream, particularly downstream of the wetland.  The other families are a bit more slender.

ORDER: Odonata
SUB-ORDER: Anisoptera
FAMILY: Gomphidae
 

Like other Odonata, members of this family have four wingpads. Like members of the sub-order Anisoptera, the abdomen terminates in five points. What distinguishes Gomphidae from Aeshnidae is the  fact that Gomphidae has clubbed antennae.

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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