Otter Creek

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: Uenoidae
GENUS: Neophylax

Neophylax are a stouter trichoptera. The head is scrunched in between the arms and the anal hooks are connected directly to the bottom of the abdomen instead of to the prolegs. There are small ovals on the ventral abdominal segments. 

Because our samples were taken in summer, there were large numbers of Neophylax prepupae found.  We anticipate that there will be fewer present in the streams in late September and many of those sampled will be at the pupal or adult stage.  Samples taken in October would tend to have more empty cases. 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: Coleoptera 
FAMILY: Elmidae
GENUS: Optioservus

The larvae of Optopservus have a closed coxae, as determined by the straight definition between segments on the ventral side of the pronotum.

The adult Optioservus have a compact appearance, especially the head and thorax. There are also dorsal ridges and a characteristic diamond-shaped feature observable in the dorsal view. SMC

ORDER: Diptera
FAMILY: Simuliidae

What's not to like about blackflies?  Our second most common dipteran.  Rather like a bowling pin with hands attached at the head end.  We have not identified them past family at this point, but it is in the long-term plan.
NABS

© 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.

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: Ephemeroptera
FAMILY: Ephemerellidae
GENUS: Drunella

The mayfly Drunella is distinguished by its large femoral “biceps” on the front legs. The body rests in one plane with the biceps at the same level as the head and junction with the thorax.

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