Many misconceptions about pest management persist, particularly around mosquito control. Here we address some of the more common myths.

Myth: The City treats the river for mosquitoes

Edmonton’s thirty plus species of mosquitoes develop in standing water sites where, except for one species (Coquillettidia perturbans), all larval and pupal stages must breathe air using the undisturbed surface tension of the water. These stages cannot survive in flowing water or even choppy open water on a lake.  Flowing water habitats are more suitable for other biting flies such as black flies. 

The reason that adult mosquitoes are relatively common in Edmonton’s river valley system is that these are harbourage areas for adult mosquitoes which cannot generally tolerate drier conditions in the less treed uplands.  Summer flowers in the valley also provide a succession of nectar sources that sustain the mosquito’s energy requirements.

Myth: Bats and purple martins control mosquitoes

Like most predators, these insectivores are opportunists feeding on a wide variety of flying insects, but searching for the most energy efficient food catch they can find.  Locally, little brown bat scats do show remains of mosquitoes, but this is usually insignificant compared to moths, mayflies and various midges that swarm over larger bodies of water.  Purple martins also like to catch larger prey such as dragonflies. 

Well designed bat and purple martin boxes may not reduce mosquitoes compared to other flying insects in your yard, but they are certainly encouraged for wildlife conservation.

Myth: City mosquito spraying kills off mosquito predators like dragonflies

The City’s mosquito control program only targets larval stages of floodwater mosquitoes that develop in standing water habitats after snowmelt or a summer storm has raised the water level to flood and hatch their eggs.  This egg hatching requirement confines them to temporary and semi-permanent standing water habitats. Because of their transient nature, biodiversity in these short-lived aquatic habitats is relatively low.  These habitats dry up in the fall, precluding organisms like dragonflies, that require more than a full year of development in the aquatic stage. 

Edmonton's mosquito management program encourages dragonfly development by avoiding mosquito control in more permanent water bodies.