A long winter, late spring and wet summer have combined to create an usual emergence pattern among mosquitoes this summer that has left many Carver County residents dealing with a season’s worth of the pesky insects in a matter of a just a few weeks.
The city of Watertown has received numerous calls and complaints this month from local residents regarding an unusually high number of mosquitoes, and the Metropolitan Mosquito Control District (MMCD) says it isn’t surprised. While the MMCD says the overall number of mosquitoes probably isn’t any higher than normal this year, the emergence of several varieties all at once has been a nuisance for those who love to spend their Minnesota summers outdoors.
As the season wears on, that nuisance could turn into real danger as the risk of the West Nile virus increases later in the summer. A sample of mosquitoes in Carver County was recently the first in the metro area to test positive for the virus this year.
“We’re not necessarily seeing more mosquitoes than is average, but what is happening is that the season was delayed by a couple weeks because of unusually late snow and a very late spring,” MMCD Public Affairs Associate Mike McLean said. “That’s really collapsed the season down, and we’re seeing big spikes in mosquito numbers throughout the metro area. It’s not so much that there are more of them; it’s that there’s more of them together at the same time. It’s an interesting phenomenon.”
McLean said that different varieties of mosquitoes typically hatch at different times of the year. Usually, an aggressive variety known as spring mosquitoes hatch around Memorial Day, and often trigger the first batch of mosquito complaints. Later, floodwater mosquitoes tend to develop in standing water that is often left over from melted snow.
This year, a late spring followed by torrential early-summer rains have left standing water everywhere. The result was the hatching of spring and floodwater mosquitoes all at once earlier this month, instead of in phases.
“It’s been a challenge,” McLean said. “It’s been a really intense year.”
McLean said the wet weather this year is only part of the reason for the recent swarms of mosquitoes, and to truly understand the increase, one must actually look back over the last several years. McLean said that when heavy rains and flooding follow several years of drought — as has been the case in Minnesota in recent years — it can mean a rapid increase in mosquito numbers.
That’s because mosquito eggs can remain viable more than a decade. Floodwater mosquito eggs that were laid during the last flooding incident typically lie on dry land, unhatched, until that area floods again.
“When you have a year where it’s breaking drought and there’s a lot of standing water, a lot of mosquitoes are coming from eggs that were laid the last time the water was that high,” McLean said. “You end up with an explosion in those peskier summer-time mosquito numbers.”
Mosquito concerns haven’t gone unnoticed by Watertown city staff, which has fielded phone calls from residents asking if there is anything the city can do to help control mosquito populations in parks, at ball fields, and in their own back yards. In actuality, mosquito control is handled by the MMCD, which has been aggressively targeting the pests. McLean said the organization has covered 150,000 acres so far this year with it’s helicopter treatments, which is already 3/4 of the roughly 200,000 acres it covers each year.
The MMCD, created in 1958 by the Minnesota State legislature, serves the seven-county metro area, including Carver County. The district is governed by 18 county commissioners from those seven counties, including Carver County Commissioner Jim Ische — who is serving as the MMCD chairman this year — and Carver County Commissioner Tom Workman.
The MMCD is funded by taxpayers, with the funding included in the “Special Taxing Districts” portion of property tax statements. The owner of a $250,000 home, for example, pays about $11.50 per year.
The MMCD uses a variety of methods to control mosquito populations, including helicopter treatments, which are used to control larval mosquitoes. Helicopters apply a dry pellet to wetlands, making use of a natural soil bacterium or a mosquito growth regulator to prevent larval mosquitoes from becoming biting adults. The helicopters do not spray insecticides to control adult mosquitoes.
Instead, the MMCD attempts to control adult mosquitoes by fogging cities throughout the metro area by using either ground vehicles or backpacks. All Mayer streets within city limits were fogged on Monday, July 8, and many areas in Watertown that were reported to the MMCD to be particular problem areas were sprayed Tuesday, July 9. That control effort did not cover all Watertown streets, but did include the areas around many public outdoor summertime hotspots. Exact areas that were sprayed can be found on the MMCD Web site.
The Watertown city council spent time discussing the mosquito issue during its July 9 meeting, particularly as it relates to the city’s annual summer festival, which is quickly approaching this weekend.
“With Rails to Trails on the horizon, city staff has looked into some alternative mosquito control measures that we can try to get in place to make sure downtown is as comfortable as it can be,” said Watertown City Administrator Luke Fischer, who added that the MMCD was also aware of the upcoming event. “They intend to do some additional spraying for that event. I know that our baseball fields and softball fields have also been noted in their file as areas where we would like some additional treatment.”
Watertown City Council member Steve Washburn noted that the mosquitoes have been so troublesome lately that he and his family have been able to spend little time in their yard. He urged residents to continue to report troublesome areas to the MMCD, which can be done on the organization’s Web site, www.mmcd.org.
However, Washburn also indicated his concern that the issue goes beyond just a simple annoyance.
“To me, it’s more than just a nuisance issue,” Washburn said. “This is a public safety issue.”
The MMCD agrees. Its control measures are designed in part to relieve metro-area residents of the annoyance that comes with bites, but also to keep the public safe. West Nile season is rapidly approaching, and the virus has already been found in a sample of Carver County mosquitoes.
McLean said that’s no reason to panic — it’s typical to see positive tests this time of year — and that the connection to Carver County doesn’t mean mosquitoes are any more dangerous in this area than any other part of the metro area. It just happens to be where this sample was collected.
However, as the summer wears on and West Nile dangers increase later in the season, McLean also said it’s important to take common sense precautions.
“It’s only a matter of time before humans are exposed,” McLean said. “Bites in May and June are really pesky, but they aren’t carrying the disease yet. Now we’re starting to see signs of West Nile creeping into birds and mosquitoes. … We don’t want to raise unnecessary alarms, but really start taking seriously packing that mosquito repellent.”
Contact Matt Bunke at [email protected]