KSTP: Hot, dry weather helping Minnesota mosquito season
June 18, 2021
NMCAW: Mosquito Field Technicians Lane Bagus and Max Nivala
June 22, 2021
MMCD Field Operations Supervisor Brian Feldhake demonstrates a "sucomatic" device that collects resting mosquitoes.
Results from the June 8th Monday night surveillance show mosquito numbers have increased throughout the district and particularly high Culex mosquitoes
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.
The results from the June 8th surveillance published by the MMCD entomology lab show that adult mosquitoes increased pretty significantly throughout the District. According to MMCD Assistant Entomologist, Dr. Scott Larson the previous week had only 3 traps that collected more than 300 adult mosquitoes and this week there were 22. Most of these mosquitoes collected in CO2 traps were Aedes vexans or summer Aedes mosquitoes. Coquillettidia perturbans or cattail mosquitoes are emerging across the district, but are still at relatively low levels.
According to Larson, the big story for last week is probably the large number of Culex mosquitoes being captured all across the District. Not only were there high numbers in the gravid traps, but there were also high numbers in the CO2 traps. Culex mosquitoes (Cx. pipiens, Cx. restuans, and Cx. tarsalis are the main species found in Minnesota) are of particular concern because they are the primary vector of West Nile virus (see vector update below).
Black flies, or biting gnats, have almost gone away completely with the exception of a few small pockets near Jordan in the Southwest metro.
VECTOR UPDATE: First samples of Culex mosquitoes tested for West Nile virus were negative
Last week MMCD Vector Ecologist Kirk Johnson began conducting RAMP tests on mosquitoes to detect the presence of West Nile virus recently. 55 samples of Culex mosquitoes were tested and all results were negative. According to Johnson, "One factor that is on our side is that we are following two consecutive seasons of very low West Nile virus transmission and there were likely low numbers of WNV infected adults that overwintered."
There were more mosquito pools available to be tested this week due in part to warm temperatures and Johnson anticipates that the heat may contribute to earlier than normal samples to test positive for WNV. Even if we see an early rise in infection rates, it's still too early to forecast transmission this year. Johnson says "Our best preventive measures include all of the larvicide work we do to reduce Culex populations; in catch basins, stormwater structures, artificial habitats, wetlands and ditches."
Learn how MMCD conducts RAMP tests for West Nile virus.
Mid-June is peak season for deer tick nymphs.
MMCD tick specialist Janet Jarnefeld reminds everyone to be alert for ticks as we are heading into the peak season for nymphal deer ticks - in a typical year nymphal deer tick numbers peak in mid-June. Based on early surveillance, adult ticks appear to be out in lower numbers this year. According to Jarnefeld, "While I do not like making predictions as there is still way too much that we don’t know, I’d said on a June WCCO story, this is playing out as a lower than typical tick year."
The best way to prevent tick-borne disease is to check yourself, your kids, and your pets any time you've been near tick habitat. Learn more about the tick surveillance program at MMCD.
For the latest updates on mosquito control, disease activity, and planned treatments, follow MMCD on Twitter or Facebook.
