Experts warn of concerning side effect of warming winters in Michigan: 'Worse ... for human health'

Winters in Michigan have been getting warmer, and experts are warning that rising temperatures could make mosquito season in the Midwestern state especially troublesome. 

What's happening?

The Detroit News reported that locals began experiencing mosquito bites as early as February this year, which Michigan State University entomology professor Edward Walker said was "almost a ridiculous thought."

Mosquito season in the fall has also become longer. 

"I can say without any doubt that the mosquito season in the fall is lasting at least a month longer than it did 20 years ago," Walker told the outlet, explaining that urban sprawl and improperly disposed of trash are likely exacerbating the issue, along with changes in climate.

In addition, warmer temperatures have allowed mosquitoes to expand their territories to previously inhospitable areas.  

For example, the Aedes aegypti and Aedes albopictus mosquitoes have appeared in Michigan over the past 10 years, and they like to reproduce in "less natural environments," as reported by the Detroit News. This means trash is serving as a perfect breeding ground for the pests. 

Meanwhile, environmental degradation means mosquitoes that are already common in Michigan, like the Culex pipiens species, have fewer natural predators, like minnows and dragonfly larvae. 

"When everything is working in harmony, it's easy to overlook that those things [in the ecosystem] were really beneficial and providing a service that maybe we weren't aware of," said Marie Russell, a postdoctoral fellow at the Oak Ridge Institute for Science and Education in North Carolina. 

Why is this important?

Mosquitoes are vectors for diseases that can severely harm human health, including West Nile — commonly carried by the Culex pipiens species, per the Environmental Protection Agency. According to the World Health Organization, around 80% of people who are infected are asymptomatic, but the virus can cause fatal neurological disease. 

In Michigan, where West Nile is the most common mosquito-borne disease, changes in climate seem to be contributing to bigger and more frequent outbreaks. 

"It's usually associated with hot and dry early summers followed by heavy rains early on," Michigan Department of Health and Human Services medical entomologist Emily Dinh told the Detroit News. 

It's natural for heavy rainstorms to occur from time to time, but warmer global temperatures have led to more severe and frequent extreme weather events. This appears to be the case in Michigan. The Environmental Protection Agency notes that much of the state has gotten 2 to 3 degrees Fahrenheit warmer over the past 100 years, and heavy rainstorms are becoming more common. 

Meanwhile, the state's newcomer mosquitoes are known to spread Zika, chikungunya, yellow fever, and dengue, the latter of which is surging in record numbers in the Americas early in 2024. While the natural weather phenomenon El Niño played a role, the outbreaks also appear to be connected to our planet's changing temperatures. 

The WHO notes most people are able to recover on their own from dengue, but the disease is also more dangerous the second time around. 

What can be done about this?

Russell told the Detroit News that picking up litter and restoring natural habitats can be effective ways to control mosquito populations. These actions eliminate sites where the pests can breed and support predators that keep things in balance. 

As individuals, we can ensure that we are properly recycling or disposing of trash when enjoying local recreation spots. Choosing native species for our yards and gardens can also help. 

Russell also suggested that insecticides can be an effective solution for junkyards, where large amounts of waste are supposed to be stored.

"We know that chemical insecticides are not great but some of the mosquito-borne pathogens are worse, you could argue, for human health," she said. 

Scientists have also been working on chemical-free solutions to control disease-carrying pests. 

A solar-powered "Guardian Toad," for example, disrupts mosquito reproduction by paddling around containers with standing water, thus preventing the insects from laying their eggs. In Brazil, genetically modified mosquitoes are showing promise in controlling a dengue outbreak. 

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