Wednesday, September 24, 2008

Oxyethira video (Hydroptilidae)

I found this video on youtube of the larvae of the genus Oxyethira of the microcaddisfly family (Hydroptilidae). Hydroptilids are the worlds smallest caddisflies, and happen to be the largest family of Trichoptera, with over 1400 named species worldwide. This particular video shows the fifth instar larvae. I know this because during the first through 4th larval instars, Hydroptilids are free living and do not make a case. When they molt to the 5th instar, their abdomens become much larger and sometimes grow to bizarre shapes, and they also produce a portable case in which they eventually pupate. These cases are usually unique for each genus. Oxyethira makes a wine bottle shaped case of silk, in which one end is a narrow neck and the other like the base of a wine bottle. Both sides are open, and as you can see in the video the larvae can easily switch sides from inside the case.

Above: The common genus Hydroptila. The cases are constructed of sand and silk, and have a characteristic, slightly angled "roof" on one seam.

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