With rising temperatures following a steady stream of rain last month, entomologists say Chicago-area residents should expect to soon see an influx of the dreaded insect of summer — the mosquito
Cooler temperatures this spring have kept the current mosquito population at bay, but abatement districts are seeing millions of breeders now that temperatures are rising, said Mike Szyska, director of the Northwest Mosquito Abatement District.
Late May's high rainfall caused the hatching of floodwater mosquito eggs, which can lay dormant in soil for years, Szyska said. While it takes about 24 hours from the time rain hits the eggs for them to hatch, weather conditions determine how long it takes them to turn into adult, biting mosquitoes, he said.
Judging from rainfall totals from the last week in May and rising temperatures this week, Szyska estimates residents should start seeing more pests beginning the middle of next week.
But, exactly how many is hard to say. If there were no treatment throughout the Chicago area, there could be at least 1,000 mosquitoes per half acre, he said. Although it's impossible to treat every area of standing water, abatement districts throughout the Chicago area are out in full force this week to try to ensure those numbers will be smaller, he said.
"It's very difficult to keep up with, especially after monstrous rains like this," Szyska said.
One bit of good news, entomologists say, is that these bugs are more of a nuisance than a threat. The burgeoning population isn't the Culex, the West Nile-carrying bug. Those, commonly called the Northern house mosquito, don't breed in large numbers until the weather is consistently warm and dry. The current crop of mosquitoes, called floodwater mosquitoes, are typically harmless but love to bite, said Melanie Arnold, spokeswoman for the Illinois Department of Public Health.
In fact, experts aren't seeing many West Nile-bearing mosquitoes right now, as heavy rain often washes their larvae away, said Ephantus Muturi, interim director of medical entomology for the Illinois Natural History Survey at the University of Illinois at Urbana-Champaign. Residents don't have to worry about West Nile-carrying mosquitoes until the weather is dry and the temperature is consistently at or above 70 degrees, optimal breeding environments, he said.
Just how many West Nile-capable carriers the Chicago area will get is hard to predict, Szyska said, adding that besides newly hatched mosquitoes, there are also some left over from last year. Unlike the floodwater mosquitoes, the mosquitoes that can carry West Nile hibernate through the winter in areas with high humidity, like tree holes and sewer tunnels, he said.
Chicago's sporadic weather patterns make forecasts for this mosquito population difficult, said Dave Zazra communications manager for the North Shore Mosquito Abatement District.
"It can be maddening," said Mark Baker, chief of field operations for the Northwest District.
In DuPage County, the Health Department's website features an interactive, color-coded map displaying the various mosquito traps that are checked regularly for West Nile virus. The last check of the county's more than 30 traps at the end of May showed no signs of the disease.
This year's heavy winter snows won't play much of a role in the mosquito population. While the snow worked with rain to give mosquitoes more breeding space, cold temperatures and wind kept the most of the mosquitoes from hatching, experts said.
Last summer was warm, but it was very wet and the area was flooded with nuisance mosquitoes, Arnold said. The 2005 and 2006 summers were hot and dry, perfect for West Nile-carrying mosquito breeding, and more than 200 human cases of West Nile were recorded in each of those years. As of Tuesday, there have been no positive West Nile tests this year, said Arnold of the state Health Department.
Still, West Nile is still out there and "people do have to continue to protect themselves," Szyska said.
Residents should check their yards for standing water, said Michael Slamecka, biologist for the South Cook County Mosquito Abatement District. Mosquitoes lay eggs in stagnant water containers, including pet dishes, gutters, tire swings and children's toys. Wearing bug repellent is the most important step, Slamecka added.
While some may try to avoid being outside when mosquitoes are active, that's often hard to do as floodwater mosquitoes are out all day, Zazra said. But house mosquitoes — those that carry West Nile — are most active from dusk to dawn.
"You still want to go out and enjoy the short summers that we have in Chicago," Zazra said.
Tribune reporters Kate Thayer and Bridget Doyle contributed to this report.
Cooler temperatures this spring have kept the current mosquito population at bay, but abatement districts are seeing millions of breeders now that temperatures are rising, said Mike Szyska, director of the Northwest Mosquito Abatement District.
Late May's high rainfall caused the hatching of floodwater mosquito eggs, which can lay dormant in soil for years, Szyska said. While it takes about 24 hours from the time rain hits the eggs for them to hatch, weather conditions determine how long it takes them to turn into adult, biting mosquitoes, he said.
Judging from rainfall totals from the last week in May and rising temperatures this week, Szyska estimates residents should start seeing more pests beginning the middle of next week.
But, exactly how many is hard to say. If there were no treatment throughout the Chicago area, there could be at least 1,000 mosquitoes per half acre, he said. Although it's impossible to treat every area of standing water, abatement districts throughout the Chicago area are out in full force this week to try to ensure those numbers will be smaller, he said.
"It's very difficult to keep up with, especially after monstrous rains like this," Szyska said.
One bit of good news, entomologists say, is that these bugs are more of a nuisance than a threat. The burgeoning population isn't the Culex, the West Nile-carrying bug. Those, commonly called the Northern house mosquito, don't breed in large numbers until the weather is consistently warm and dry. The current crop of mosquitoes, called floodwater mosquitoes, are typically harmless but love to bite, said Melanie Arnold, spokeswoman for the Illinois Department of Public Health.
In fact, experts aren't seeing many West Nile-bearing mosquitoes right now, as heavy rain often washes their larvae away, said Ephantus Muturi, interim director of medical entomology for the Illinois Natural History Survey at the University of Illinois at Urbana-Champaign. Residents don't have to worry about West Nile-carrying mosquitoes until the weather is dry and the temperature is consistently at or above 70 degrees, optimal breeding environments, he said.
Just how many West Nile-capable carriers the Chicago area will get is hard to predict, Szyska said, adding that besides newly hatched mosquitoes, there are also some left over from last year. Unlike the floodwater mosquitoes, the mosquitoes that can carry West Nile hibernate through the winter in areas with high humidity, like tree holes and sewer tunnels, he said.
Chicago's sporadic weather patterns make forecasts for this mosquito population difficult, said Dave Zazra communications manager for the North Shore Mosquito Abatement District.
"It can be maddening," said Mark Baker, chief of field operations for the Northwest District.
In DuPage County, the Health Department's website features an interactive, color-coded map displaying the various mosquito traps that are checked regularly for West Nile virus. The last check of the county's more than 30 traps at the end of May showed no signs of the disease.
This year's heavy winter snows won't play much of a role in the mosquito population. While the snow worked with rain to give mosquitoes more breeding space, cold temperatures and wind kept the most of the mosquitoes from hatching, experts said.
Last summer was warm, but it was very wet and the area was flooded with nuisance mosquitoes, Arnold said. The 2005 and 2006 summers were hot and dry, perfect for West Nile-carrying mosquito breeding, and more than 200 human cases of West Nile were recorded in each of those years. As of Tuesday, there have been no positive West Nile tests this year, said Arnold of the state Health Department.
Still, West Nile is still out there and "people do have to continue to protect themselves," Szyska said.
Residents should check their yards for standing water, said Michael Slamecka, biologist for the South Cook County Mosquito Abatement District. Mosquitoes lay eggs in stagnant water containers, including pet dishes, gutters, tire swings and children's toys. Wearing bug repellent is the most important step, Slamecka added.
While some may try to avoid being outside when mosquitoes are active, that's often hard to do as floodwater mosquitoes are out all day, Zazra said. But house mosquitoes — those that carry West Nile — are most active from dusk to dawn.
"You still want to go out and enjoy the short summers that we have in Chicago," Zazra said.
Tribune reporters Kate Thayer and Bridget Doyle contributed to this report.