According to new research by scientists at NC State University, insects and other arthropods play a major role in getting rid of New York City's trash: Assuming that bugs take a break in the winter, scientists calculated that the critters on the medians along 150 blocks in the Broadway/West Street corridor can consume more than 2100 pounds of discarded junk food every year. That's the equivalent of 60,000 hot dogs!
To figure out how much city arthropods ate, the researchers placed two measured piles of food—one in a cage, where only arthropods could get at it, and another out in the open—at certain sites on street medians and in parks, then returned after 24 hours to collect what food, if any, was left over.
On the first day of the study, the researchers left the piles in Highbridge Park in the city's Washington Heights neighborhood; they returned the next next day to find the cage—which had contained a piece of a Nilla Wafer, a Ruffles Original potato chip, and a slice of Oscar Meyer turkey hotdog—empty. "I thought there was a problem," Elsa Youngsteadt, NC State research associate lead author on the study, which was published in Global Change Biology, wrote in a blog post. "This was a cage cobbled together out of a fry basket from a restaurant supply store plus a square of hardware cloth, and it was firmly tacked to the ground with landscape staples. With its snug, quarter-inch mesh, it should let most insects move freely, while keeping vertebrates out."
Could mice or rats have somehow gotten into the cage? The researchers moved the cage, fortified it further, and returned the next day to find it swarming with ants—pavement ants (Tetramorium species), to be precise. "At sites where we found pavement ants, more got eaten," Youngsteadt wrote. "They love nesting near pavement, so they’re more common in medians than in parks. (But Highbridge Park had them, explaining its big, median-like appetite.)"
The researchers found that arthropods on medians ate two to three times more junk food than arthropods in parks. And by cleaning up after us, bugs are serving another purpose, too: They're helping to limit populations of animals like rats and pigeons, which also eat our food waste. "Both groups of animals (bugs and vertebrates) want the stuff we drop," Youngsteadt wrote. "In other words, they compete for it; what one group gets, the other group doesn’t. I would love to know how much of that uncaged food went to ants and how much to rats—and whether that depended on the kind of food, the size of the food, the time of day, the habitat. But those are goodies for another study someday."