Academics Admission Student Life Athletics About Saint Michael's News & Events

Site codes explained and mapped  (under mapping resources tab)

Macroinvertebrates home

Streams project

 

Stevens Brook (LCD_StvBrk_59)

These are the most common macroinvertebrates identified from samples from Steven's Brook by the intersection of Kellogg and Jewett in Saint Albans.

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

This family of net-spinning caddisflies is very abundant at several sites.  They are important filtering collectors and are quite common at urban and agricultural sites where particles of organic material can be important food resources.  Genus-level identification is possible for mature specimens and we will include the genera we found at your site if possible. Commonly found genera include Cheumatopsyche, Ceratopsyche, and Hydropsyche. Less commonly, we have found Arctopsyche and Potamyia.

When using the key, some features that are challenging to see are the forked trochantin and the paired sclerites in the folds between segments.  Other, more easily seen key features include filamentous gills on the abdominal segments and the sclerotization of the dorsal surfaces of all three thoracic segments. Keep in mind that with smaller or more immature specimens, genus-level ID may not be possible.


Aquatic Bioassessment Laboratory, California Digital Reference Collection

ORDER: Trichoptera
FAMILY: Glossomatidae

Larvae in this family build domed cases made of small rocks, and are often wider at segment 5. The pronotum is covered in dark, sclerotized plates, but there are either no sclerites on the mesonotum, or the mesonotum is unsclerotized with the exception of a few patches. The anal proleg is broadly joined to segment 9; the anal claw has one or more accessory hooks. The  pronotal excision is small (approximately 1/3 anterolaterally) to accommodate the coxae.

Commonly encountered genera include Glossosoma and Agapetus.

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: 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.

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: 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.
NABS


NABS
ORDER: Trichoptera
FAMILY: Brachycentridae 
GENUS: Brachycentrus

These larvae are typically found with their legs extended out of their case for feeding. The cases are square in cross section and made of plant materials. Brachycentrus has 2 large sclerites on the metanotum. In fresh samples (preserved for less than one week) these organisms often have a pale green tint.

 

ORDER: Coleoptera
FAMILY: Elmidae
GENUS: Stenelmis

The larvae of Stenelmis, as in Ordobrevia, have a sternum on the ventral side of the pronotum. The main difference between the two genera is in the antennae- the second segment is less than twice as long as the first in Stenelmis.

The adult Stenelmis has a clear separation between the thorax and abdomen as well as a more distinctly separate head as compared to other genera. SMC

ORDER: Diptera
FAMILY: Tipulidae
GENUS: Dicranota

Dicranota can be distinguished by the two tails and their comb feet. There are usually 5 pairs of prolegs on the abdomen with combs on them. In addition, the posterior portion of the abdomen often has a slight swelling. SMC

 

ORDER: Diptera

Pupae from the order Diptera are typically found in small numbers at every site. These can be identified further, but we do not.

 

Photo Source:

http://commons.wikimedia.org/wiki/File:Leech_blutegel.jpg

Phylum: Annelida
CLASS: Hirudinea
 

Leeches have bodies with 20 or more segments and a ventral suction disk on at least one end, though sometimes on both ends.

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: Trichoptera
FAMILY: Hydroptilidae
Genus:
Hydroptila

Members of this family, commonly called micro-caddisflies are typically found in soft pouch-like cases made of minerals. As the common name suggests, they are tiny, but have rather bulbous abdomens. Like the Hydropsychidae, the dorsa all three thoracic segments are sclerotized. Unlike them, however, they have no filamentous gills on their abdomens. The genus Hydroptila in particular is characterized by having three fleshy projections at the end of the abdomen.

ORDER: Coleoptera
FAM
ILY: Psephenidae
GEN
US:
Ectopria

False water pennies are less circular than true water pennies, and come to a blunt point at the back end. They appear to have serrated edges and lack gills. 

Another genus encountered in this family is Psephenus.

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).
2008 Saint Michael's College
One Winooski Park, Colchester, Vermont, USA 05439 | 802.654.2000 |
Privacy Policy