Culiseta morsitans (Theobald) is a mosquito vector of eastern equine encephalitis virus. Gravid Cs. morsitans were collected from resting shelters during June–September of 2004 and 2005 associated with a natural breeding area known as Toad Harbor-Big Bay Wildlife Management Unit in Oswego County, New York. Specimens were held individually in water-filled containers to encourage egg laying. Conditions in captivity provided three site options for oviposition, as follows: on a paper filter above the water line, on the filter at the water line, or on the water surface. Oviposited eggs were counted, as were eggs found retained in abdomens of dissected females. Fecundity for 181 female Cs. morsitans was based on the total egg count for each female. There were 89 females that oviposited ≥ 1 egg and produced an average of 158.4 eggs ± 4.9 eggs with a range of 51–318 eggs. Of the 89, there were 63 captive females that oviposited all their eggs, producing a mean of 160.4 ± 4.9 eggs, range 81–254 eggs. There were 62 egg masses oviposited above the water line within a range of 2–68 mm (average = 24 mm), 12 egg rafts or oviposition of scattered eggs directly on the water surface, and no rafts oviposited on filter paper directly at the water line. Wing length was used as a measure of mosquito size. The mean wing length for 154 females was 4.37 ± 0.02 mm (range, 3.8–4.9 mm).