Dr. Gerry Wegner
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For years, I have attended conference presentations about the biology and control of red imported fire ants (Solenopsis invicta), commonly referred to as RIFA. I listened with just half my usual interest because, hey, fire ants are just a Southern problem,
right?
Well, now I know better. This fall, Jeff, a technician colleague, brought me a few worker ants for identification. I knew
immediately they were not one of the usual peridomestic Ohio ant species.
Jeff told me the ants were trailing prominently in an indoor planted landscape at a commercial account. Neither Jeff nor his
partner technician, Steve, got stung while handling the ants at this account and at the time, no customer contacts on-site
had complained about getting stung. He and Steve had spot-treated the activity sites.
It was time to get input from fire ant experts. I asked Jeff to gather as much information as he could: When were the ants
first encountered? What was the source of plants and landscaping materials used in the interiorscape? I re-examined the specimens
more closely, shifting my gaze back and forth between the microscope, a dichotomous key to common invasive ants and descriptive
text in three reference books. Fortunately, most of the specimens were in excellent condition, making it easy to discern specific
anatomical features. 
Fig. 1. Red imported fire ants lack a prominent tooth on the underside of the first node.
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THE SEARCH IS ON The specimens were decidedly fire ants, but I could not discern which species. Were they RIFA or Southern fire ants (S. xyloni)? Both species are found in Florida, which happened to be the source of the infested plant material.
I called Dr. David Oi, a researcher with the U.S. Department of Agriculture's Agricultural Research Service at the University
of Florida in Gainesville. He emphasized the importance of notifying USDA's Animal and Plant Health Inspection Service (APHIS)
of the situation because transportation of a species of economic importance across state lines was at issue. I told Dr. Oi
that representatives of our account were taking the appropriate steps and that I ought not become involved in the matter at
their request.
Fig. 2. Face of red imported fire ant showing three clypeal teeth, indicated by arrows.
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My next phone call was to Dr. John Klotz, an entomology professor at the University of California-Riverside. He referred
me to his colleague, Dr. Les Greenberg. I asked Dr. Greenberg whether he could examine some e-mailed images of my specimens.
He agreed and coached me in what to look for in distinguishing the two species. I found a match for RIFA, which turns out
to be the more common of the two species encountered in Florida. He also corroborated my findings when I e-mailed him Figures
1 and 2.
Jeff gave me the name of the nursery in Florida from which the infested plants originated and the month in which the plants
arrived at our account. I learned that the ants had been introduced to the building more than a year earlier and had indeed
stung some of the employees — they never reported the incidents. The fire ants clearly benefited from months of noninterference:
Reports that came to me in the days that followed indicated several mound nests had been located in the interiorscape soil.
It was time to consider management strategies appropriate to the situation.
TREATMENT METHODS I was relieved to learn there was a fire ant bait registered for use in Ohio and selected accordingly. Then I brainstormed
with Jeff and Steve about where the granular bait would be appropriate for use at this account.
