The rain has revived Minnesota's mosquito populations
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Lab workers sorting mosquitoes by species at a survey facility in Houston. Photo: Kirk Sides/Houston Chronicle via Getty Images
Soggy spring weather has been an unexpected boost for the Twin Cities' mosquito populations.
State of play: The Metropolitan Mosquito Control District (MMCD) had been predicting a slow start to the season, but a rainy spring has negated the effects of a historically dry winter on Minnesota's unofficial state bird.
Why it matters: Aside from driving a big market for anti-itch cream, Tiki torches, and citronella candles, mosquitoes carry diseases like West Nile.
What they're saying: Mosquito eggs hatch in water, so precipitation is crucial for their populations, MMCD public affairs director Alex Carlson told Axios.
- The first broods generally hatch after early snowmelt raises water levels in ponds, marshes, swamps, and rivers — but without much snow, MMCD had previously thought an early-season mosquito surge wasn't likely.
- "But that was quickly changed by the rain in March, April, May, and June," Carlson said. "Basically, anywhere that can hold water is holding water right now."
Reality check: While their levels are higher than originally anticipated, human-biting mosquitoes are still showing up in MMCD's surveillance traps at levels right in line with the 10-year average for this time of year.
"What's interesting," Carlson adds, is that the consistent rains haven't led to an above-average year so far.
- Mosquito eggs can survive for three to five years until they get the water they need, but MMCD officials speculate that Minnesota's persistent drought means there are also fewer eggs waiting to hatch.
What they're watching: Carlson said MMCD is not expecting a big mid-summer spike from "cattail mosquitoes" — nicknamed for their breeding grounds — which could keep overall numbers at or below average.
The big picture: Over the longer term, climate change is lengthening Minnesota's mosquito season, which could make the state more hospitable for tropical, disease-carrying species.
To do your part to help manage the mosquito population:
- Get rid of standing water in containers, clogged gutters, low spots in your yard — anything that will hold stagnant water.
- Don't flush any larvae you find; they can survive in the sewer. Just leave them outside.
- Look for the EPA certification on bug sprays and pest control devices. This means they've been tested for safety and effectiveness, Carlson said.
Go deeper: Our colleague in Atlanta has a DIY contraption that he says works. Build at your own risk.