Monday, December 11, 2017

Lessons from Rodent Academy

Dr. Bobby Corrigan delivers his introduction to rodents sharing his favorite Sherlock Holmes quote. Much of the class is
devoted to training students to be better observers of rodent behavior. 

Bobby Corrigan refers to himself professionally as a rodentologist, though he's slow to admit as much to just anyone. He describes the typical conversation with someone next to him on a plane, or at a casual encounter at a party:

"So, what do you do for a living?" 

"I'm a rodentologist."

"Oh, how nice!" [crickets]... End of conversation.

I for one am glad the world has rodentologists. Because we need them. Without a rodentologist we couldn't have offered the three day course held last week at the Texas A&M AgriLife Center at Dallas. And without rodentologists we wouldn't have a clue about how to manage these intelligent but unwelcome house guests.

When I first met Corrigan at Purdue University in the early 1980s he was the only grad student working on rodents in a department of entomologists, a pattern that seems to have continued throughout his career.  

"Despite their acknowledged importance from a public health perspective," Corrigan said, "I saw there was little in-depth information about how to control rodents for people working on the city, county and school level." While there seemed to be lots of money and resources for insect-related pest problems, Corrigan was always asking "What about the rodents?"

Corrigan's persistence  paid off in 2003 when he was awarded a $5 million grant working with the City of New York to help establish the Rodent Academy course. Since then, the NYC Academy has been offered twice a year, filling up every time it's offered. The classes have become legendary for their intense classroom sessions and nighttime tours of Norway rat-infested streets, parks and alleyways of the big Apple. Since it was first offered the Academy has trained over 2,000 people in rodent management.

In recent years Corrigan has helped put on Academies in other locations including Seattle, Philadelphia, San Diego, and Washington, DC. Last week was the first time the course was offered in Texas.  And if the response of this year's attendants of the first Texas Rodent Academy is any indication, the Academy will be offered again.  

Corrigan seemed pleased with his first Texas class. Very well organized [by Extension program specialist Janet Hurley], excellent faculty, "Almost like an experienced academy," he said.

Although Dallas differs from NYC in the density and intensity of infestations, rodent problems are based on the same template, says Corrigan. "Even though the two cities feel different and look different, from the rodent's perspective both make good homes.  Both produce garbage and have plenty of food in dumpsters, and both cities have people who litter, so the Academy curriculum works [in Texas as well as New York].  

An important part of the class arrives when students break into
groups to develop a rodent management plan for the IPM House.
One way that Texas does differs from New York is in rodent species composition. New York has massive problems with the large, bold Norway rat, as well as the adaptable and highly invasive house mouse.  While both rodent species are present in Texas, the secretive and acrobatic roof rat predominates in most urban communities here. One of the guest speakers for this year's Academy was Mike Swan, of Entex Pest Solutions in Richardson.  Swan showed pictures and described a recent encounter with a massive roof rat colony in a local suburb.  After an intense baiting campaign, the company ended up removing over 700 dead roof rats from several adjoining businesses in an upscale neighborhood.

Emory Matts, of Steritech/Rentokil in Dallas also assisted Corrigan with his talk on protecting our food supply from rodents.  Touting the U.S. Public Health Service Food Code as "a good read," Matts surveyed many of the laws protecting food safety and provided IPM tips for inspection and control programs.  He emphasized the importance of knowing who is auditing your customer's food handling premise, because standards for indoor and outdoor bait placement and service frequently differ depending on the auditing agency.

Application Rates

After establishing that nearly everyone in the class regularly used rodent baits in their business, Corrigan stumped the group with a simple question, "What's the appropriate application rate for rodent bait?" [crickets]...  The number one reason for poor rodent control, he said, is failure to estimate rodent density, and follow label application rates (oz. bait/area treated) based on the estimated rodent population.  Typical rodenticide labels require users to apply 3 oz bait/30 ft (for low infestations), up to 16 oz bait/15 ft (severe infestations). Very few PMPs know these application rates, with the result that few apply sufficient bait when going after an established rodent population.

Dry Ice

One of the biggest developments in rodent management in many years occurred this summer, Corrigan said.  After prolonged discussions with the National Pest Management Association, in late June 2017 the U.S. EPA approved a label for "Rat Ice," dry ice for asphyxiating rodents in burrows. When placed into a rodent burrow and covered with soil, pelleted dry ice is an extremely effective and low-risk treatment for ground-nesting rodents.  Until now, the only barrier to its use was that dry ice was not registered as a pesticide and technically could not be used in commercial pest control.  

While there is still some confusion about where and how to purchase dry ice legally for rodent control, an EPA-approved label for "Rat Ice" is now available. Bell Labs is sponsoring the new label as a service to the industry and says it is working on state registrations.  Bell Labs will provide a more comprehensive update, including launch details, soon, according to a recent news update in PCT magazine. [Note: According to Texas Department of Agriculture regulator, Michael Kelly, the Rat Ice label has been registered in Texas.]


In Corrigan's opinion, another one of the most significant improvements in rodent management in recent years is non-toxic baits for biomonitoring. These non-toxic baits allow PMPs to minimize risk of baits to non-target organisms while identifying when and where rodents are present. Many of the newer baits also include bio-luminescent dyes that become brilliant "glowscats" when captured in the glow of one of the new LED blacklight flashlights.

Jose Dolagaray from Arrow Exterminators
in Georgia displays a dead roof rat discovered
during his outdoor inspection of the IPM
Experience House.
These non-toxic, bio-luminescent baits now act as tracking baits, providing information about three critical items: a) high-activity rodent trails; b) distances traveled, and; c) possible zones where nests are located. Consequently, glowscats provide clues to help you maximize effectiveness of trap and bait stations placements. Another benefit is when bioluminescent baits are placed outdoors only, glowscats found indoors provide evidence of penetrations in the building envelope.

As an added bonus, Corrigan said that in every instance that he's observed, rats prefer these toxicant-free baits. They are inevitably the first baits eaten from a bait station. He believes they can help jump-start bait-shy rodents to feed when placed in stations on the outside of rodenticide-containing blocks and soft-baits.

IPM House

The IPM Experience House provided the hands-on setting for excursions on each of the three days. Because the house is situated next to an un-mowed culvert, and bounded by a minimally maintained tree nursery and garden area, rodent life outside was... interesting. Students caught glimpses of cotton rats, Sigmodon hispidis, and saw unmistakable roof rat burrows, runways and rub marks around parts of the building perimeter. A water filled bucket proved deadly for an inquisitive roof rat and provided an opportunity for participants to practice their rodent ID skills. Most agreed that being able to practice their new observation skills around the IPM House was a valuable part of the training.

The class covered much more than can be covered here, exhausting students by the end of the third day. If you want to learn more about rodents before the next academy comes along, consider purchasing a copy of Corrigan's very informative book: Rodent Control: A Practical Guide.

For more information about IPM Experience House and upcoming PMP classes, check out the website and consider signing up for the mailing list. A new listing of 2018 classes is coming soon.