War Against Mosquitoes

Cape May County’s marshes are full of man-made canals, outfall ditches, and ponds, many of which were created over 100 years ago to reduce the mosquito population. How can canals, outlets, and ponds achieve this goal?  
“People in this county live in a place that has much lower mosquito populations than any time in the past, but they don’t fully understand what it took to get there,” said Dr. Peter Bosak, director of Cape May County’s Department of Mosquito Control (DMC), in reference to the war against mosquitoes he and his team fight every working day.  
The answer lies in the 17-acre headquarters of DMC, a property which once housed World War II German prisoners of war and Civilian Conservation Corps (CCC) workers.   
Cape May County is home to 45 species of mosquitoes. Managing mosquito populations in this swampy county is a task which requires 15 full-time staff, eight to 10 year-round workers, millions of dollars, heavy machinery, dedicated scientists, and thousands of work hours per year.  
From egg to adult, some mosquito species run through the entirety of their lifecycle in five to seven days. If DMC did not exist, the mosquito population would be exponentially larger.
Bosak said as far back as the 1800s, visitors would come from large cities for cool, clear air, but were deterred by the county’s “massive” amounts of mosquitoes.  
“People don’t get a sense of just how much water is in this county. We are literally living in a giant swamp,” he added. Of this water, only a small portion produces mosquitoes. High marsh, where water can’t flow and is left to stagnate, can serve as breeding grounds for mosquitoes.  
Much of the high marshland that exists does not occur naturally. According to Bosak, Spartina patens, or “salt hay,” is a marsh plant that was highly valuable from the 1800s through the mid-1900s … salt hay is very slow to decay and was used as the base for dirt and gravel roads and weed control in place of the mulch used today.  
Salt hay farms were planted on marshes all over the county. Salt hay can only grow on high marsh, and to accommodate demand, salt hay farmers had to create dikes to increase the elevation of marshland. Much of the high marsh that produces mosquitoes wouldn’t exist were it not for the farming of that once-valuable plant.  
The last salt-hay farm in the county, Hand’s Farm, closed in the early 2000s. The farm would produce “billions” of mosquitoes in a bad week, Bosak said.  
Bosak noted how easy it is to tell the difference between high marsh and low marsh. Salt hay is easily visible via DMC’s surveillance helicopter because of its bright-green coloring. The department surveys the county every week via helicopter and other means every day during the week for areas of mosquito-rife stagnant water.  
Many of the ditches and canals that exist in the county were dug over 100 years before the creation of the Cape May County Mosquito Extermination Commission in 1915. A state law was passed in 1912, which required every county to have a mosquito-control commission. 
Before the mandate, people knew that mosquitoes were a problem, but there was no singularly coordinated effort to fix it. Many different groups set out with an objective: to remove water that produces mosquitoes.
Long, closely-spaced canals, which Bosak said were created “in a systematic grid fashion,” represented the county’s best efforts to drain stagnant water before better methods were known.  
Hundreds of thousands of feet of ditches were once dug by hand, and later by horses and donkeys which pulled large plows behind them through the muggy earth.
The department uses large machines, the newest of which displaces its weight so evenly that it leaves less impact than a human footstep, to drain stagnating water.
Outlets and ditches are carefully calculated before they are created. Nothing is done without extensive planning, scientific research, and investigation.  
Many of the ditches drain into artificially created standing ponds. Those ponds, created in the low marsh, flood completely during storms and high tide. The receding tide fills the ponds with fish that eat mosquito larvae that drain into the pond via the ditches from the high marsh. These ponds also serve as places for birds to feed and rest.  
This technique is part of a larger effort to leave a minimal impact on the marshes. Pesticides used by the DMC, Bacillus thuringiensis israelensis (BTI), are natural.
The department uses a naturally occurring bacterium in a granular solid. Synthetic pesticides that may harm the environment are used as a last resort.  
DMC’s headquarters contain a microbiology lab, where hundreds of mosquito samples are taken from all over the county every day and are tested for viruses that cause human disease. Cape May County is the only county in New Jersey with a BSL3, “Biosafety Level 3” lab.
If mosquito samples, each with about 50 individuals, test positive for contagions, that specific location and species are targeted for control. Without these efforts, mosquito-carried diseases would likely be much more common in the county.  
The department battles high-tide flooding. These tides flood high-marsh areas, where water will stagnate and produce mosquitoes. This is a battle that is exacerbated by climate change, according to Bosak.
Water is creeping into areas it would never have previously, including forests and the sides of highways. This water must be drained or treated by the DMC, or billions of mosquitoes will take flight.  
Bosak said these problems are increasing in frequency: “We’re all aware of climate change. Scientists around the world are sounding the alarm. Whether or not you believe it, that’s a personal choice. But as scientists, we see the dramatic changes in water levels in many habitats. Habitats are changing and the DMC must adapt its control activities in step.”
Ed Sokorai, the department’s wetlands specialist, continued the sentiment: “At some point, the water will be at the very edge of the Garden State Parkway. We see water encroaching in places we’ve never seen it before … The land is sinking before our eyes …” As coastal waters climb higher, the marshland which makes up the county is also sinking, Sokorai warned.  
As a result, the county’s barrier islands are flooding with greater frequency than ever before. Bosak and his team spend an increasing amount of time on the islands draining stagnant water from roads and road ends.  
Bosak said his team is hampered greatly by wetland permits and bureaucracy. “What slows us down is the whole process of getting permits to do what we are trying to do. Sometimes it takes months and months.”
In the interim, Bosak said mosquitoes multiply rapidly while his team is stuck waiting for permits.  
About his team, Bosak said, “They’re all unsung heroes. I guess all of us are.”