May is Lyme Disease Awareness Month. Protect Yourself from Ticks!
May 15, 2024
Weekly Update – May 20th – Spring Mosquitoes Already Above Average for 2024
May 29, 2024
Black fly larvae has been increasing in rivers and streams and staff have been out to monitor and treat.
The first week of District-wide surveillance shows some mosquitoes starting to appear and black flies already abundant in the south and west metro.
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.
Last Monday, May 13th was the first night of District-wide surveillance with CO2 traps, gravid traps, and sweep nets collecting mosquitoes and black flies throughout the Twin Cities. Overall mosquito numbers were low throughout the District with most CO2 traps collecting fewer than 50 mosquitoes, though a few in northern Anoka and Washington Counties collected several hundred.
According to MMCD assistant entomologist Dr. Scott Larson, "last week we mostly saw large numbers of spring Aedes mosquitoes. These mosquitoes can live for months, take multiple blood meals, and are implicated in Jamestown Canyon virus transmission, so it’s important to control these as larvae before they emerge and hang out until August." In 2023 we collected some of the highest numbers of spring Aedes in District history due to the large amount of snowfall the previous winter. This past winter we did not have as much snow, but spring rains have taken us out of drought conditions and could contribute to emergence of more spring species.
Summer Aedes are not abundant yet, but the lab has reported finding quite a few larvae in the samples being brought back, so they will likely be more present in coming weeks. We are also seeing some areas with high black fly (or "biting gnat") activity. Larson says, "Black flies (likely Simulium venustum, a human-biting small stream species) were abundant in quite a few locations in the southern portion of our District and locally in some other areas."
Here are the mosquito trap counts from last Monday, May 13th:
Helicopter activity will be continuing this week.
It's been a busy season already for helicopter treatments with over 75,000 acres of treatments already completed in 2024. That is slightly ahead of where we were at this point last year (about 65,000 acres in 2023) and has a lot to do with the frequent rains we've had in April and May.
This week helicopters are treating ponds and wetlands that are holding cattail mosquito larvae based on surveillance we did in the fall. Cattail mosquitoes hatch in August or September and overwinter as larvae, using the stems of vegetation (like cattails) to breathe during the winter before emerging in a single brood around the beginning of July. Later in the week treatments may be necessary to respond to rainfall that is expected.
We have a new widget on the MMCD homepage to indicate whether or not helicopters are active. Check it out!
Deer ticks are active! People and pets are at high risk of Lyme disease transmission in May and June.
We've already mentioned that May is Lyme Disease Awareness Month and last week had an entire blog post dedicated to it. We've had numerous reports from field staff and the public that tick are quite active right now so it's always a good reminder to take the necessary precautions - use flea and tick preventative on your pets, put bug spray on yourself and permethrin on your clothing and gear, and avoid long grasses and wooded or brushy areas.
Get more details all about Lyme disease at our post from last week.
MMCD in the News
Last week Jonah Kaplan from CBS Minnesota stopped by to talk about how the MMCD Entomology lab works to identify and reduce mosquitoes and shares some tips that you can use:
