Hydroptilid: Larval Morphology

Wiggins (1996a) provides an excellent overview of the larval morphology of all North American genera. Lepneva (1964) and Wells (1985) give overviews of larval morphology of the Russian and Australian faunas respectively.

Species–Specific Characters that may be used in future keys are described here, especially if regional faunas are well known.

Oxyethira pallida fifth instar. Note portable case is present only in the fifth, or final, instar.

Oxyethira pallida third instar.  Note the lack of a portable case during the first through fifth stadia.

Dorsal prothoracic sclerite and foreleg of Ochrotrichia sp. from a small woodland stream.  The larva is from exposed bedrock over which shallow water flows.  Note strong ventral tibial spur.

Mandibles of 6 species of the genus Hydroptila (from Keiper 1998) common in Ohio. A, H. ajax, B. H. armata, C. H. consimilis, D, H. hamata, E, H. perdita, and F, H. waubesiana. Note differences in dentition and number of posterolateral setae.

Foreleg Morphology: It has been long understood that the ventral projection of the tibia of some hydroptilid genera (e.g., Hydroptila, Ochrotrichia, Oxyethira) is an adaptation which aids larvae grabbing algal filaments. Setation, size of the projection, and spines on the projection appear variable among species. (Top, Hydroptila armata, Bottom H. perdita. Modified from Keiper and Foote [1999]).

The Prosternum of Hydroptilidae usually hosts 2-3 sclerites which vary in shape, size, and coloration among species. In some larvae, these sclerites may be very pale and difficult to discern. Prosternal sclerites of Ochrotrichia xena (Keiper 1999) and Hydroptila armata (Keiper and Foote 1999). These images illustrate the venter of the prothorax with the coxae removed.

Dorsal Abdominal Sclerites:

The dorsum of the abdomen (e.g., Hydroptila and Ochrotrichia ) frequently bear sclerotized rings or plates, but these are represented as faint rings in some species (e.g. Flint and Herrmann 1976, Keiper 1999).

Other characters such as sclerite coloration (Ross 1944) certainly vary between species, but may be variable geographically. Some characters require intensive procedures such as clearing and mounting on slides for detailed examination; these include palp and antennal morphology. Little information on these structures is available presently, and warrant further attention.