New York City is in a war against rats, and its latest weapon is contraception.
Mayor Eric Adams appointed a “rat czar” — Kathleen Corradi, officially known as the “director of rodent mitigation.” The former elementary school teacher, who developed the “Zero Waste Schools” program, is being paid $155,000 a year to do the job.
Aside from essentially appointing a battlefield general, Adams — a self-proclaimed hater of rats who has participated in public rat execution — treats the conflict with high-stakes terminology, consistently referring to it as a “war.”
As dramatized as it seems, the issue of rat overpopulation in New York is real and pervasive. In 2022, the year before Corradi was hired, rat sightings in New York grew to 60,000, double the amount from 2021.
Such drastic growth is a prime example of the prolific reproduction rats are capable of. A female rat typically gives birth to six litters per year, with each litter consisting of up to 12 pups. It only takes nine weeks for a rat to reach sexual maturity, and with such rapidity, a population can go from two rats to 1,250 in a single year. From there, the population swell can be exponential.
The introduction of contraceptives comes as an alternative to a history of pesticide-focused pest control, both in New York and across the world. As the rat population growth shows, an alternative method is proving necessary — pests are simply evolving past those methods of control.
“Evolved resistance to pesticides is now recognized as one of the most significant problems of modern times,” said Stephen Shuster, professor of invertebrate zoology at Northern Arizona University, speaking on a study he conducted on pesticides and their alternatives.
Shuster found that since pesticides are rarely capable of eliminating an entire pest population, the natural outcome is evolved resistance. Contraceptives, however, are more strategic in their control, cutting the population by targeting specific age groups and the genetic factors that develop resistance most efficiently.
“Our overall conclusion is that we can mitigate the [resistant] selection … by changing the usual goal of pest control treatments,” Shuster said. “Instead of attempting, and ultimately failing, to destroy or sterilize an entire pest population, we advocate the use of contraceptive treatments that primarily act to reduce these species’ rates of reproduction.”
Contraceptive use provides a promising alternative to pesticides, and it’ll be welcome in the midst of a war with no discernible end in sight. It isn’t new, however.
In 1967, then-NYC Governor Nelson Rockefeller greenlit a program to “curtail rat reproduction with minute doses of drugs like those used by women as oral contraceptives.” Such measures were reintroduced as recently as 2013. Neither brought the resounding end to the rat problem researchers and legislators were seeking.
The 2013 experiment was done with the same remedy as that of 2024: ContraPest. In its coverage for the present-day experiment, the New York Times describes ContraPest as “a rat contraceptive” with bait containing “active compounds that target ovarian function in female rats.” This bait will come in the form of pellets said to be “full of fat and salt … so delicious that rats preferred them to digging through the trash.”
The product has a strong track record. Parker Eco Pest Control in Seattle, Washington, reported a 91% rat population decrease after a seven-month test trial. A study into the efficacy of ContraPest in a “complex urban environment” found several promising numbers, including a 67% reduction in seasonal population peak after 133 days of the product’s usage.
New York is a different beast, however.
Shaun Abreu, the bill’s sponsor, spoke on the need for consistency, saying that NYC’s past tries were foiled by a lack of persistence both in effort and in method. Those previous attempts sometimes used liquid bait instead of pellets or failed to pair the attempt with “trash containerization,” which Abreu said gives rats fewer alternatives for food.
Regardless of how it looks, it’s a new offensive attack. For the front of Adams, Corradi and the New York citizenry seeking to cleanse the streets of rodents, it’s necessary; as the original rat czar job offering said, the army of rats is “cunning, voracious, and prolific.” The 2024 NYT piece was right in describing birth control as “the next frontier” in the war on rats.
Perhaps the new effort will be a game-changer. Perhaps, like the others, it will ultimately fall short of its desired conquest, giving way to the next strategy. The exhaustive search for the solution could be the key to victory, however much it might feel like a shot in the dark.
“In the words of Albert Einstein,” said Loretta Mayer, who founded SenesTech, the company behind ContraPest. “If we knew what we were doing, they wouldn’t call it research.”
