It was a Saturday morning at the beginning of October. Larry Heaney, a resident of Evanston for almost 30 years, was starting a survey of his neighborhood. Going down the alleyway behind his home, Heaney checked out the trash bins at each residence, and 10 out of the 30 bins had one thing in common: They each had holes in them. He also noticed that several bins were overflowing with trash.

The abundance of garbage could be easily explained. Trash pickup in Heaney’s neighborhood occurs every Monday, but the bins are already full by Saturday. But who was the culprit for the holes? They could have been squirrels, which wouldn’t have been too concerning. The most likely assailant, however, is more damaging to urban life, known for overpopulation, carrying disease and being incredibly resilient, lining up perfectly with Heaney’s observations.

That assailant is rattus norvegicus – the brown rat.