EMERGENCE COMPOSITION AND PHENOLOGY OF TIPULIDAE (DIPTERA) FROM A TROPICAL RAIN-FOREST STREAM AT EL-VERDE, PUERTO-RICO

This paper represents the first study of the phenology of adult crane fly emergence from any tropical site. Twenty species of crane flies we re collected by an emergence trap from February 1990 through January 1 991 at Quebrada Prieta, a second-order stream in the Luquillo Mountain s in northeastern Puerto Rico. Four species of Limonia comprised 75% o f the individuals, and one species alone, L. (Geranomyia) virescens (L oew), comprised 47%. Crane fly emergence was continuous throughout the year but showed distinct flucuations which might be seasonal, includi ng greatest number of emerging adults in January through March, and fe w individuals from June through August. Fluctuations in emergence may be related to disturbance in the stream due to intense summer storms a nd resultant scouring of rock surfaces. Grazers on benthic algae inclu ded 68% of the crane fly individuals.