Beaver Brook

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.

© Aquatic Bioassessment Laboratory, California Digital Reference Collection

ORDER: Ephemeroptera
FAMILY: Ephemerellidae
GENUS: Ephemerella

Ephemerellidae mayflies have no gills on abdominal segment 2 and usually have dorsal abdominal spines. Mayflies in this genus have long intersegmental setae that extend laterally and well-developed maxillary palps.

© US EPA

ORDER: Diptera
FAMILY: Tipulidae
GENUS: Hexatoma

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

ORDER: Coleoptera
FAMILY: Elmidae
GENUS: Stenelmis

Riffle beetles appear in the streams as adults and larvae. The larvae of Stenelmis have a sternum on the ventral side of the pronotum.

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: 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: 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 Ceratopsyche.  To 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

ORDER: Trichoptera
FAMILY: Rhyacophilidae
GENUS: Rhyacophila

Rhyacophila is a common caddisfly in Otter Creek. In our lab it is known as the "Michelin Man" due to its large white banded body. It has a very obviously checker-patterned head. It also has a terrifying anal claw which has large accessory hooks. SMC

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: Diptera
FAMILY: Ceratopogonidae

Members of this family look like very straight Chironomidae. They are very long and thin with a distinct head capsule and no prolegs. SMC

ORDER: Coleoptera
FAMILY: Psephenidae
GENUS: 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.