Flooding brings in a whole new hoard of mosquitoes, some that have been waiting for years to hatch and bite. Floodwater mosquitoes are a breed that lay their eggs at the edges of floodwaters, so that when they recede, the eggs dry up. The next time the water rises, they hatch. Director of the Southeast Missouri Arbovirus Lab Christina Frazier says they chase and bite, but don’t transmit disease.
“There will be hoards after a flood. There will be a big boom of these this summer. If we are getting lots of mosquitoes, these are the type we will get,” Frazier says, noting that they look like your garden variety mosquito, but they are different to a trained eye. Their scientific name is aedes vexans, named in part because, she says, “they are vexing biters.”
There are two other types of mosquitoes swarming the state that can transmit West Nile and other diseases, Frazier says, which is why it’s important to dump anything with standing water, use insect repellant and avoid going out at dusk when mosquitoes most often feed. One of them is known as the Asian Tiger Mosquito, the other is the aedes albopictus.
“Right after a flood, we can expect to see an increase in pest mosquitoes,” she says.
At this point in the summer, she says the St. Louis County Health Department normally would be trapping about 200 mosquitoes a night in a trap. Recently, they’re collecting more than 1,000 per night.
“Everybody should be responsible for their own yards to make sure they don’t have spots holding water,” she says, adding that’s where vector mosquitoes — disease carriers — gather and lay eggs. “Old paint cans, old swimming pools that are semi-dried up and old tires are likely culprits. If you have a lot of these items around, you are generally a breeding ground right in your own yard. We are better off if everyone cleans up their yards so we have fewer mosquitoes.” She says even a cigarette wrapper can be a breeding spot for mosquitoes.
Of the 30,000 mosquitoes St. Louis County has sent to Frazier’s lab, xix were determined to be carrying the West Nile Virus. However no mosquitoes carrying St. Louis Encephalitis have been identified yet this summer.
To avoid getting bit:
• Wear mosquito repellent when outdoors
• Avoid going out from dusk to dawn, when mosquitoes feed
• Wear long sleeved shirts if you are outdoors