Anecdotal evidence has suggested that the American serpentine leafminer (ASL), 'Liriomyza trifolii' (Burgess), is resistant to registered insecticides in the Niagara Region of Ontario. The ASL has become resistant to currently registered insecticides in the United States, but previous to this study the same could not be said about Canadian ASL populations. In Canada, the ASL is primarily a pest of greenhouse chrysanthemums and gerberas. This study demonstrated resistance to insecticides registered in Canada for ASL control in some Niagara Region ASL. Alternative management tactics for ASL resistant populations were investigated. The non-registered reduced risk insecticides chlorantraniliprole and spinosad were determined to be effective at controlling ASL larvae. Chlorantraniliprole was determined to be compatible with the biological control agents 'Diglyphus isaea' and 'Steinernema feltiae. S. feltiae' infected ASL prepupae but is cost prohibitive. Wilt-Prut ® and VaporGardo® anti-desiccants deterred ASL for up to 6 d. MilStop® was not an effective adulticide for ASL.