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Chicago’s new rat control approach is poison that makes them infertile

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Chicago has tried just about everything to control a burgeoning rat population fueled by a construction boom and a mild winter. None of it has worked in a city seemingly overrun by the rodents.

Now, City Hall is trying something old and something new: A poison designed to make rats infertile, and dry-ice that produced promising results in parks and medians before the city was forced to stop the rat-suffocation experiment after learning the dry ice had not been approved by the U.S. Environmental Protection Agency.

The poison is called Contrapest. It will be tested for six months at a waste transfer station at 34th and Lawndale, where 25 bait boxes will be installed, each equipped with feeding tubes that encourage rats to take poisonous bait.

If it works as advertised — by rendering rats infertile unable to breed — the poison could become a “regular method used in other enclosed and contained areas” that serve as breeding grounds for rats.

And now that the EPA has signed off on dry ice, the city will start using it again to control the burgeoning rat population in Chicago parks.

“The dry ice method serves as a safe and quick approach that essentially puts rats to sleep before they perish,” Streets and Sanitation Commissioner Charles Williams was quoted as saying in a press release. “We found that it is an effective and safe tool in our parks, where our residents frequent” and often leave behind food, wrappers and other trash that rats love to eat.

City Hall will also restart an intensive public outreach program to cut off the food source for rats — by persuading residents to secure their garbage, take down backyard bird feeders and clean up after their dogs and cats, even in their own back yards.

After baiting alleys, “Target Rat” posters will be tacked up again, along with an updated “Don’t Feed the Rats” poster. City crews also will distribute brochures advising Chicagoans on rodent control.

Implied, but not stated, is the looming threat of hefty fines against dog owners who refuse to clean up the backyard mess. That ordinance remains stalled in a City Council committee.

Ald. Michele Smith (43rd), whose ward was overrun with rats after the demolition of Children’s Memorial Hospital, said Lincoln Park residents have recently reported success with yet another proven rat killer: feral cats.

After receiving training, homeowners and renters “put them in cages in their alleys and garages” and leave the door open, allowing feral cats to “establish a territory that drives out” rats, the alderman said.

“People are just thrilled with it,” Smith said.

It’s not the first time City Hall has used rat poison to render rodents infertile and therefore reduce the rat population.

Three years ago, then-Ald. Bob Fioretti (2nd) urged Emanuel to use sterilization bait to get a handle on a rat explosion. After meeting with SenesTech, an Arizona-based research firm that had been studying the liquid bait, Fioretti said he was convinced that it could work in Chicago.

Nine months later, Emanuel started testing the poison manufactured by the same Arizona company that makes Contrapest. Fioretti, who would go on to run for mayor in 2015, said, “I told you so.”

Dry ice costs $10 for 20 pounds, compared to $57 for the same amount of poison.

City officials say they still need to bait alleys, where dry ice is not as effective because rats burrow into the concrete.

But they argue that dry ice works in parks, medians and planter boxes, where the earlier test produced a 60 percent reduction in burrows.

In addition to dry ice, rat poison, cart repairs and public education, Emanuel has tried “coyote management” and added 10 baiting crews.

The mayor’s 2017 budget also resurrected the stand-alone bureau charged with overseeing the city’s war on rats.

The number of rat abatement requests phoned into the city’s 311 non-emergency number is actually down 2.5 percent from the same period last year, according the Streets and Sanitation spokeswoman Sara McGann.

From Jan. 1 through July 24, 311 received 20,846 complaints, down from 21,365 abatement requests during the same period last year.

Williams has credited the city’s five-day response for the slight improvement.