Jul 8, 2008 10:41 pm US/Central
Good Question: Why Do Mosquitoes Bite At Dusk?
(WCCO)
In Minnesota, summer is the time to enjoy the great outdoors and be enjoyed by swarms of hungry mosquitoes. But why is it that mosquitoes seem to mainly come out at night?
"I hate them. I get really bad bites all the time," said Sarah Krefting, a college student from Minneapolis. "I get bit to death in the evening but never during the day."
The answer to the question is complex, according to Sandy Brogren, entomologist with the Metropolitan Mosquito Control District.
"There's been a lot of studies to find out when mosquitoes are active but I don't know if anyone really determined out why that is," said Brogren.
Volunteers for MMCD collect samples of mosquito populations every Monday at night, when mosquitoes are most active. They try to kill adult mosquitoes by using a special fog at night as well.
"I think they're reacting to the environment; they're reacting to the twilight and the temperature," said Brogren.
Scientists have studied extensively the timing of mosquito activity; they pinpoint the busy time in Minnesota at 35 minutes after sunset. In early July, that would be around 9:30 p.m.
"They like it to be cool and moist, not real dry and hot. So they'll be out at night when it's cooler and the winds are lower," explained Brogren.
Because mosquitoes are so tiny, they are particularly vulnerable to hot, dry weather. When it's higher than 90 degrees, mosquitoes can be killed off. The same happens when it's below 50 degrees, she explained.
During the day, mosquitoes are not sleeping but they are in a state of rest.
"They're in wooded areas where it's dark and cool, and they'll be protected from hot sun and any other wind," said Brogren.
She also said that some bug scientists believe mosquitoes have learned to come out at dusk, because there's a higher concentration of people available to snack on.
"I don't know that they're thinking those things but they do like to come out at a time when they're probably more hosts available," she said.
(© MMX, CBS Broadcasting Inc. All Rights Reserved.)
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