Southeastern Pennsylvania’s mix of rolling hills, river valleys, and humid summers creates an ideal environment for mosquito populations. From suburban neighborhoods around Philadelphia and Chester County to wooded wetlands along the Delaware River, mosquitoes are a year-round concern from late spring through early fall.
More than 60 mosquito species have been identified in Pennsylvania, but a handful dominate daily life for residents. These are the species most often encountered in backyards, parks, and neighborhoods.
One of the most aggressive mosquitoes in Southeastern Pennsylvania.
Distinctive black-and-white striped body and legs.
Bites primarily during daylight hours, especially mornings and late afternoons.
Breeds in small amounts of standing water — gutters, buckets, planters, and birdbaths.
Extremely common in urban and suburban areas throughout the Philadelphia metro region.
Rare but occasionally reported in warmer areas of Southeastern PA.
Prefers human dwellings and shaded outdoor spaces.
Daytime biter known for transmitting diseases like Zika and dengue in tropical regions (not currently a threat locally).
Among the earliest species to appear each spring.
Breeds in temporary water sources like rain-filled ditches, floodplains, and grassy depressions.
Aggressive biter, active mainly at dusk and dawn.
Populations increase rapidly after heavy rainfall or flooding events.
Nighttime biter active from dusk through dawn.
Breeds in stagnant, organic-rich water — birdbaths, storm drains, and clogged gutters.
Primary carrier of West Nile virus in Pennsylvania.
Common across both rural and suburban communities.
