Weekly Update – August 27th – Mosquito Numbers Increased in the Last Week of August
September 5, 2024
Weekly Update – September 10th – Mosquitoes Right at Average with a Few Weeks Left
September 13, 2024
Mosquito numbers are back down quite a bit this week with September starting pretty dry.
Mosquito numbers begin the end of season decline as we begin Fall.
Every Monday night starting in mid-May through September, the Metropolitan Mosquito Control District sets out a variety of mosquito and black fly traps throughout the district and employs a network of sweep net collections done by employees and volunteers. Any insects collected are brought back to our lab on Tuesday to be identified throughout the week with maps published to show current mosquito and black fly activity.
After several months of above average rainfall, September has started out refreshingly dry in the Twin Cities. There have been no days this month where the District has received more than an inch of rain and most days have had no precipitation at all, which is a nice change of pace from August where more than half of days received at least some precipitation and there were multiple 1"+ rain events in the first week. Mild temperatures and dry conditions have brought down overall adult mosquito numbers throughout the District and we are unlikely to see a significant spike again as we head into the last few weeks of surveillance.
According to MMCD Entomologist Dr. Scott Larson, "Without any significant rain in the forecast, the numbers of adult mosquitoes will continue to decrease across the District. Even the Culex mosquitoes aren’t present in the large numbers we have seen for most of this year. Black flies are almost nonexistent, so I hope that brings some relief to those areas that had it so bad earlier this year."
MMCD will continue to conduct adult surveillance as long as conditions indicate mosquitoes will still be active in measurable numbers. Look for overnight temperatures to dip below 50 degrees or extended periods of dryness which help us determine when we stop our weekly collections.
Here are the maps from Tuesday-Wednesday, September 3rd-4th:
As mosquito numbers decline, ticks begin to re-emerge for the fall.
As mosquito numbers decline and temperatures begin to cool off, the risk for mosquito-borne disease steadily abates. The risk for West Nile virus will remain through September, so it's a good idea to keep the bug spray handy. However, as we transition into fall we start reminding people to take precautions against our other common local vector - ticks.
Larson reminds us, "Adult blacklegged ticks (deer ticks) become abundant again in the fall as they look for another blood meal. If they aren’t successful, they’ll just hunker down for the winter and try again next spring." With the re-emergence of ticks comes the risk of the diseases they carry. It's good not to forget that just because the mosquitoes and other noticeable insects have gone away, does not mean ticks aren't active. Last year, with the mild temperatures we experienced, ticks were found into December!
Lyme disease is the most common tick-borne disease (learn all about it on our post for Lyme Disease Awareness Month back in May). The second most common is anaplasmosis and the third most common is babesiosis, which was recently featured in an article from the Washington Post.
Reduce your risk of tick bites by wearing light-colored clothing, staying on the trail, using insect repellent, and always checking yourself, your kids, and your pets after being in tick habitat.
