Boston’s Use of Dry Ice for Rodent Control Is Placed on Temporary Ban

By Beth Treffeisen

A successful new program of using carbon dioxide in the form of dry ice for rodent control was recently put on hold after it came to the attention of the State’s Department of Agricultural Resources that it was unclear as to whether or not dry ice needed to be registered as a pesticide.

City workers under the Inspectional Service Department (ISD) have been burrowing holes and then filling them with dry ice before covering them with dirt. If rats enter those burrows or are already in them, they die from asphyxiation.

ISD Commissioner William Christopher said it is cheaper than poison and is less likely for a child or animal to ingest it.

“It is a road block,” said Christopher. “But the problem ebbs and flows.”

He said that in the winter the complaints go down but in the spring they will probably see an up-tick with the warmer weather.

A pesticide is defined, by both state and federal level, as anything that claims to kill, repel, prevent or mitigate the growth of a pest. This also includes the manner as part of services to control a pest.

When a product is being used as a pesticide it first needs to be registered through the Environmental Protection Agency (EPA). Once registered it then needs to be registered with the Pesticide Division department at the state level to be in accordance with the Massachusetts Pesticide Control Act.

“The EPA has reached out to us and they want to work with us,” said Christopher. He added that the Department of Agriculture, who ordered the stop of the dry ice has also been in corporation with the City.

Christopher is unsure how long it will take to get through the process of registering dry ice as a pesticide, but he hopes to resume using it by spring.

There is no way to tell the real number of rats in Boston but, the 311-complaint line and app for cell phones tracks the amount of complaints based rodent activity, which can also include mice.

In 2016, there were 3,133 rodent activity complaints filed to the city. That is up from 2,170 in 2015.  Part of this big up-tick Christopher attributes to the roll out of the 311 app for cell phones, making it even easier for people to file a complaint. Before, residents had to make an extra effort to make a phone call.

“There has definitely been an upward trend over the last five years,” said Vic Palermo from Ultra Safe Pest, who has been in the businesses for about 20 years and does residential work in the Boston area, mainly in Beacon Hill and the Back Bay.

He said that brownstones for some reason seem to play a big part in the problem. The basements and crawl spaces tend to lend themselves for a great place for rats to burrow and create tunnels.

Trash is another big attractive and if a couple of conditions come together with food and water – that’s it, the rats are in heaven.

Over the past five years Palermo said businesses have started to come back after the recession. He said, “There has been an increase in tourism in the city and the more crowded the area is the more garbage we have.”

John Bozarjian from Johnny B’s Pest Control that does residential rodent control in the Greater Boston area has seen a pattern in the last two to three years where rodents have gotten worse.

“It’s not only a Boston issue anymore and that’s a real concern,” said Bozarjian. “We’re receiving the most calls we’ve ever seen from the suburbs. The rats are getting further and further away from the City.”

Bozarjian said there really is no way to tell how many rats there actually is in Boston but he estimates there’s probably hundreds and thousands of them. He said, they’re just like mice – you see one in the house and they’re probably 20 to 40 in the walls.

The main reason for the up tick he believes is because there was a warm winter last year. In New England, the cold temperatures usually knock off a lot of them he said, but last winter there wasn’t enough consecutive days with freezing temperatures.

Another reason he said is that many larger landlords or property managers are not properly taking care of their properties, leading to a lot of trash being mishandled.

“Even if you go down one street and one person calls out a rat problem, it’s usually not an isolated issue,” said Bozarjian. “If there are a bunch of people trying to mitigate the problem it only takes a couple of properties with absentee landlords to continue it.”

Within the last year, Dorchester had the most complaints with 602, followed by Allston-Brighton at 581. Back Bay had 209 complaints and the Downtown-Financial District had 180.

This ban comes at a time when rats aren’t as active due to the colder temperatures, making it a prime time to target rats that seek shelter from the harsh weather within their nests.

Bozarjian said that the City works on maintaining a lot of the burrows that are found in construction sites and parks. He said, “The timing isn’t probably great because it is a good time to combat those holes.”

Until the City can go back to using dry ice they will continue using other methods to continue to help mitigate the problem.

ISD has an outreach program with tenants on how to manage garbage and recycling. They ask residents and business owners to use proper containers and to keep them away from walls, where rats like to run up against and hide in.

Christopher said that the management of trash is the most important because it is the number source of food for the rats.

“When I see lightweight garbage bags sitting against trash cans I think that can be food for any rodent,” said Christopher.

Other methods include the use of poison in controlled environments and placing traps in strategic locations.

“Rats like to run along walls and don’t like to go out into the streets,” said Christopher. “If you see that, rats out in the middle of the day across the street, there is something going on in that population.”

Christopher said that they are happy whenever people file complaints because ISD tracks them and uses that data to maximize their resources to take care of the problem. He said, “We take a very aggressive, very positive approach to this.”

ISD is capable of giving out violations and for the most part, Christopher said, people comply once they are given.

As well, the Site Cleanliness Ordinance requires all businesses and residential locations that maintain bulk refuse apply for a license. A penalty for not holding a license or failing to operate or maintain a licensed dumpster can go upwards of $1,000 per day or result in a closure of the business for repeated violations.

To avoid rats in a backyard, make sure to use trash bins with rounded edges to avoid rodents from trying to bit their way into them. Use tight lids and keep them away from walls and other obstructions.

In backyards, make sure to take away any clutter up against the house that gives them shelter and make sure to secure any openings into the house. They also like to take shelter in low shrubbery. Rats can fit into openings as small as a half an inch in diameter.

“They’re not coming to just say hello,” said Bozarjian. “They need food and shelter and if you take that away then they won’t come.”

The Norway Rat, or brown rat, which resides in Boston, is usually found on the ground floor, or in burrows under sidewalks or outbuildings. Although they feel more at home on the ground, these rats are adept at climbing and have been seen traveling along telephone wires. They can also swim as far as a half a mile in open water.

As an adult, a Norway Rat can weigh between 12 to 16 ounces with a body length of six to eight inches long with a tail adding a further seven to 10 inches long.

They are known for carrying and transmitting diseases such as typhus fever, ratbite fever and others.

Rats constantly gnaw anything softer than their teeth, including lead sheeting, improperly cured concrete, sun-dried adobe brick, cinder block, wood and aluminum sheeting.

Young Norway and roof rats can be sexually mature and capable of mating at three months of age. After giving birth, female rats are capable of being in heat again in 24 to 48 hours. They average three to seven litters per year and have larger litters from six to 12 pups.

“Once some of the rodents are gone people get complacent again,” said Palermo. “But it’s never going to be gone. No one is going to wave a magic want and it’s going to be gone. If you don’t stay on top of it, it will come back up.”

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