Life history and case building behavior of Molanna tryphena (Trichoptera :Molannidae) in two east Texas spring-fed streams

The life history and case-building behavior of Molanna tryphena Betten from 2 spring-fed tributaries in east Texas were studied from January 1997 to M ay 1998. The 344 larvae, pupae, and adults sampled indicated. a univoltine life cycle, with an extended adult emergence period. Fecundity was 76.2 +/- 9.7 eggs per female. Larvae were recruited in spring and summer, and grew to late instal's or pupae by fall. Larvae and pupae were found mainly in th e sand substrate. Eggs, larvae of 2nd and 5th instars, pupae, cases, and ad ults are described. Case reconstruction behavior was observed and videotape d. Larvae constructed emergency cases by gluing together sand and burrowing inside to form a tube. Sand and gravel were added over the next 12 h to st rengthen the tube and add the cowl and flange typical of Molannidae.