Trash is the biggest factor in rat infestations, researchers say

Around the world, more than 35 diseases are known to be easily spread by rats and the ticks and fleas that live on them. The Black Plague, the most famous pandemic to strike mankind, was spread in part by rats stowing away on European merchant ships.

Naturally, we humans have a vested interest in keeping the little pests contained. That can be tough, though, as rats are persistent everywhere in the world, especially in urban areas.

In the city of Chicago, researchers noticed that nearly 46,000 rat complaints were lodged between April 2017 and April 2018, an increase from previous years. But do a lot of complaints really mean a bigger barrage of rats, or have people just decided to speak up more? They decided to dig deeper.

“Every city and urban property owner is required to manage rats, so our discoveries about rats in Chicagoland may be applicable to help wildlife managers and urban planners in other cities as well,” said Rebecca Fyffe of Landmark Pest Management, a firm involved in the research.

Joining Landmark were scientists from Lincoln Park Zoo’s Urban Wildlife Institute and the Davee Center for Epidemiology and Endocrinology.

The rat race

The research team trapped rats in 13 Chicago neighborhoods and compared the rate of rats caught with public data on rat complaints, incomes, rental properties and land cover. Researchers also measured the amount of garbage, clutter/harborage spots and structural integrity of buildings at each site.

Their findings were probably what you expected. More frequent rat complaints are indeed indicative of greater rat populations.

What was also clear: Sitting piles of garbage were huge indicators of rat abundance, more so than any other factor. Trash, when not securely contained, provides food and shelter to hungry rodents, so it makes sense that they’d be drawn to these neighborhoods.

It was also discovered that neighborhoods with more rental units than owned homes had more rats — but vacant lots had fewer. It drives home that rats thrive when concentrated near humans.

“This discovery is quite interesting,” said Dr. Maureen Murray, wildlife disease ecologist. “Additional research would need to be conducted but it seems that neighborhoods with high rental rates also had increased garbage and potential rat access points in alleyways, presumably due to the responsibility of maintenance being on the property owner rather than the tenant.”

What property owners need to do

Property owners need to be sure to regularly monitor their properties for signs of pest activity, or for building conditions that might make infestations more likely.

Monitoring. It’s important to regularly evaluate the property for signs of pest activity, or for building conditions that might make infestations more likely.

Use bait stations. Bait stations are boxes or tubes designed to allow a rodent to enter and consume the bait, while preventing larger animals and children from reaching inside. These can be placed strategically around the building by management, or with the help of a professional pest control service.

Apply rodenticides. Keep bait in an area that rodents frequent. Attics or crawlspaces make ideal places for bait.

Trash control. Communal dumpsters should be raised from the ground and the area should be maintained to ensure trash bags are placed inside with the lid closed, not on the ground nearby. “Stash your trash,” said Murray. “The easiest way to ensure rats stay at bay is to secure trash in closed bins.”