Q When do mosquitoes usually become active?
A It depends. Some hatch early in water that collects on the ground from melting snow, said Mike McLean, public information officer for the Metropolitan Mosquito Control District. There are 51 species of mosquitoes in Minnesota, and they can have different behaviors.
A common group of mosquitoes, called floodwater early spring mosquitoes, lay eggs directly on the ground. The eggs spend the winter under the snow; the adult mosquitoes die. When the snow melts, the mosquitoes hatch in the meltwater and begin their life cycle, emerging as adults that start biting sometime in early May.
There may be meltwater now, McLean said, but neither the water nor the temperature triggers the hatch. Instead, the eggs respond to the length of day, waiting until April to hatch. It's a safety mechanism, McLean explained.
"That way, if we get a warm week, they won't hatch and then later freeze and die," he said. "It's too early and they know it."
A little later, the eggs of mosquitoes that need higher summer temperatures will hatch. These floodwater summertime mosquitoes account for most of those that bite us, and they usually start appearing around Memorial Day.
Late in summer, we'll start seeing another species, McLean said, but they tend to bite birds rather than people.
Meanwhile, the whole mosquito population ages. Contrary to what many people think, mosquitoes don't drop dead after they bite, said McLean.
