Urban Insects Clean Up our Streets

Categorie(s): City life, Ecology, News, Waste

North Carolina State University researchers working in New York City studied the food waste disposal by insects in the city. To do their investigation, the scientists dumped food garbage in dozens of sites, within parks and in street medians. Their test materials were the stuff that is  often thrown away in the streets, like potato chips, wafers and hot dogs.

They found that insects in a single 400-square-meter street median could be consuming annually as much as 6.5 kilograms of tossed, dropped and, if there’s a bar close by, regurgitated food. Six and a half kilograms of food per street median may not sound like all that much, so the researchers extended the area to illustrate the cumulative effect: “We estimated that arthropods in the medians of Manhattan’s Broadway and West St. could remove 600–975 kg (dry weight) of food waste per year—equivalent to approximately 60,000 hot dogs, 200,000 Nilla Wafers, or 600,000 Ruffles potato chips.” We humans make a lot of garbage, relegating the insect waste removal total to what the scientists called “modest but notable. Without these animals, more littered food waste would accumulate in cities.” Which means that insects are eating food that otherwise would be attracting and nourishing rats. A heartfelt thank-you, insects.

The scientists tested both park sites and street medians expecting that the wider array of insect species in parks would be a more efficient trash-digesting community. “Theory and data from natural systems suggest that the magnitude and resilience of this service should increase with biological diversity,” they wrote. So they were surprised to find that insects in the less diverse street-median environment actually consumed up to 3.3 times more of the snacks.

A single organism may account for the medians’ superiority at making food disappear—and it’s not that quintessential urban insect, the cockroach, as one could expect. Because roaches prefer to stay inside homes, not out on the streets. No, the key critter for street-median food removal is the pavement ant.

This ant is common in urban areas, and—consistent with its occurrence in medians—prefers to nest near pavement. Their colonies average about 10,000 workers.

Pavement ants feasting on human food>>