Arosurf MSF was applied to a Massachusetts cattail marsh at 0.5 gallons/acre (4.67 liters/hectare) to prevent emergence of Coquillettidia perturbans. One application was made by helicopter and three, later in the season, by fixed-wing aircraft. The material appeared to prevent adult emergence for about a week after the helicopter application, but due to large inter-trap variances in untreated controls the results were not statistically significant. Control was spotty with the fixed-wing application. One problem was obtaining good coverage at a site with difficult aerial access, the second was the interference to delivery of the pupicide as the emergent plant canopy developed later in the season.