After Hurricane Florence brought severe flooding to North Carolina in September 2018, many inundated communities experienced a surge of mosquitoes about the size of a nickel. These pests, larger and more aggressive than typical mosquitoes, emerged from dormant eggs that had remained in the soil for up to two years.
This mosquito outbreak made headlines across the nation, but such occurrences are common in the state’s low-lying regions. Earlier this summer, Tropical Storm Debby also prompted an increase in mosquito populations in Brunswick and New Hanover counties.
Current predictions indicate that Hurricane Helene could trigger similar conditions, as forecasters expect excessive rainfall and rapid flooding in central and western North Carolina on Friday, creating an environment conducive to the proliferation of floodwater mosquitoes.
Michael Reiskind, an associate professor of entomology at N.C. State University, is an expert on mosquitoes and their ecology. Originally from flood-prone Florida, Reiskind has conducted extensive research, including a master’s thesis on dengue virus spread in Peru. He notes that while floodwater mosquitoes are generally “not a major threat to human health,” their overwhelming populations can make outdoor activities uncomfortable, especially in rural areas.
Reiskind explains that floodwater mosquitoes are characterized by their rapid development. Their eggs can survive drying conditions and may lie dormant for years until exposed to water again, leading to a sudden population spike after flooding.
While these mosquitoes are not typically associated with human pathogens, some can transmit heartworm disease to dogs, which can be dangerous but is preventable with veterinary care.
The areas most susceptible to these mosquito outbreaks in North Carolina include the coastal plain, where water tends to collect after rainfall, and any region that receives significant rain, such as the flatlands east of Raleigh.
After a significant rainfall event, floodwater mosquito species can become active in as little as four to five days, continuing as long as floodwaters persist. Cooler weather can help reduce mosquito populations, but changing climate patterns make such relief less predictable.
Reiskind cannot definitively state that floodwater mosquitoes are more aggressive than others, yet historical accounts suggest these insects are indeed more assertive. They have short lifespans and require blood for producing eggs, leading them to take more direct approaches to feeding.
To reduce the risk of mosquito bites post-flooding, residents might resort to using insecticides through aerial spraying or employing personal repellents. Wearing heavier clothing can offer some protection, though it is not particularly comfortable in high heat and humidity.
The challenges of controlling floodwater mosquitoes are heightened in rural areas due to the vast distances involved and the lack of precise prediction models for mosquito populations. There are ongoing discussions about the effectiveness and feasibility of treatment strategies in sparsely populated regions.
Researchers are exploring genetic methods for controlling mosquito populations, but floodwater mosquitoes pose unique challenges due to their biology. Although promising new approaches are being developed, substantial research is still required to create effective solutions for managing these mosquito outbreaks. Drone technology may offer a future avenue for targeted larvicide applications based on geographic data, but such innovations will take time to develop and implement effectively.