The seasonal abundance and temporal patterns of the adult sand fly (Lutzomyia shannoni Dyar) were examined at the Patuxent National Wildlife Research Refuge, MD, from August 3, 2005, to July 29, 2006. A total of 138 (53 males, 85 females) L. shannoni was collected from 4 dry ice-baited traps set at the same 4 locations throughout the study. The male:female ratio was 1:2.4. All 4 traps, separated by a maximum distance of approximately 1.6 km, operated simultaneously on the collection dates. The collection dates were spaced apart by near weekly intervals during the months of expected sand fly activity. No collections occurred in December-February. August was clearly the period of peak adult abundance as the numbers collected were significantly greater during this month than any other month of collection. Results indicate the existence of a unimodal pattern of abundance with adult emergence beginning in June and ending by September. The temporal pattern and abundance differ from what has been observed for the species on Ossabaw Island, a barrier island located along coastal Georgia, and at San Felasco Hammock Preserve State Park, Gainesville, FL. Continued research is needed to compile multiyear data to confirm the temporal abundance patterns of this species in Maryland.