The Metropolitan Transportation Authority is looking into a method of birth control for rats as it tries to get the rat population under control.
The agency is testing a bait that makes rodents permanently infertile.
The company behind the bait said it's safe for other animals and humans, and has worked well in rural areas.
But urban rats have a more discriminating palate, meaning the bait has to taste better than things like pizza or Chinese food to draw them in.
Later this month, baits with different scents and flavors will be placed at various subway trash rooms to find out what works best.
The MTA said the public will not be exposed to the bait.