Mosquito Management in the Era of Extreme Weather

As one Massachusetts mosquito-control entomologist shares. Here, a trap collection cup overflows with adult mosquitoes.

By Kaitlyn O’Donnell

Kaitlyn O’Donnell

We are aware of these changes globally, but how do we see these changes regionally, first hand? From the entomologist working for a local government mosquito control organization in the northeast United States, we have the unique ability to observe mosquito populations in a specific area over a long period of time and can pick up on trends and changes.

A lot of interesting current research sheds light on the relationship between climate change and mosquitoes. Studies have linked drought and rising temperatures to increased incidence of arthropod-vectored disease and a longer mosquito season. The mosquito population dynamics after hurricane flooding.

A Flood of Mosquitoes

With each passing hurricane season, we are reminded how the increased frequency and severity of extreme weather events are becoming the new normal. According to the National Oceanic and Atmospheric Administration, the past six years have been above average hurricane seasons, with 2020 marking the most active and 2021 the third most active seasons in recorded history. Though New England may not first come to mind when thinking about hurricane fallout in the US, the mosquito exploding populations experienced in 2021 after three consecutive storms may change people’s minds.

After repeated flooding events throughout the height of summer, the 2021 mosquito season shattered every trap abundance my district in Massachusetts previously had. I’ve never before seen so many mosquitoes squeeze themselves into one trap — so ravenous for the carbon dioxide bait that they compressed themselves, over 23,000 of them, into a 40 cubic-inch space (about the size of a sandwich container).

The vast majority of these collections were composed of floodplain mosquito species, which lay eggs in the floodplain area and waited for rain to flood the surrounding wetland with enough water for the eggs to hatch. Some collections are mainly made up of two in particular: Aedes vexans and Psorophora ferox.

Floodplain mosquito species lay in the surrounding wetland (as shown here) with enough water for the eggs to hatch. The Norfolk County (Massachusetts) Mosquito Control District has been mainly made up of two in particular: Aedes vexans and Psorophora ferox.

During the 2021 season, these two species have had three major rainfall events throughout the summer, starting with the remnants of hurricane Elsa, which hit the Northeast in early July. The mosquitoes Ps. ferox and Ae. vexans are aggressive human biters and are capable of disease vectors; their presence does not go unnoticed. These peaks in relative abundance are corroborated by an increase in resident calls for mosquito conditions around their homes and requests for an area-wide mosquito adulticiding. And with the mosquito emergences, there was never any relief.

As the mosquito control professionals, using an integrated pest management toolbox. We can predict how much flooding will cause mosquito species and be proactive about managing populations rather than reactive. We can treat these floodplains for time, resources, and weather allows, hopefully reducing the need to resort to a wide area adult.

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