The decomposition of autumn shed leaves of hackberry (Celtis occidentalis L.) and elm (Ulmus americana L.) in a gallery forest reach and a grassland reach of Kings Creek was examined by placing 24 artificial leaf packs of each species at the two stream sites. Sampling was done after 24 hours and weekly thereafter for a seven week period. No differences between elm and hackberry leaf decomposition rates were measured. The mean percentage weight loss of elm leaves during the sampling period was 90.3% of their ash-free dry weight in the gallery forest reach and 88.9% in the grassland reach. The decay coefficients were - 0.0211 and -0.0199 respectively. Hackberry leaves lost 93.8% of their ash-free dry weight at both sites (decay coefficient of -0.025). Larvae of the leaf shredding insect, Tipula, were found to influence the decomposition process in the grassland reach but not in the gallery forest reach. The Tipula larvae were estimated to exert their greatest influence on the elm leaves