New record of Psorophora howardii (Diptera: Culicidae) in Southern Ontario, Canada.

Psorophora howardii Coquillett is a large floodwater mosquito native to much of the tropical and subtropical regions of the Americas, including the southern United States, several Caribbean Islands, and portions of Central and South America. Although it is recognized as a nuisance species, substantial gaps exist in the known range of Ps. howardii. In September 2024, multiple adults (2 males and 4 females) of Ps. howardii were collected at 2 different locations in Windsor-Essex County, Ontario, Canada. Specimens were collected during routine West Nile virus mosquito surveillance using CDC miniature light traps, using UV light and CO2, and a BG-Sentinel trap. Morphological identifications were confirmed using DNA barcoding (cytochrome oxidase I gene). This constitutes the first official record of Ps. howardii in Canada and is the northernmost record for the species (~42°N latitude). The detection of Ps. howardii at 2 locations, separated by 26 km, suggests established populations are present in southern Ontario, Canada. This discovery highlights the need for continued mosquito surveillance to monitor the northward expansion of mosquito species.