An IRS worker first spotted a single bedbug at the Seattle office in October. An exterminator trapped a second bug, and that was enough for IRS officials to send in the hounds.
Exterminators use dogs trained to sniff out the insects, and the dog who canvassed the IRS offices didn't find any more bugs.
Exterminator Grant Gummow didn't help with the IRS case, but he suspects the bedbugs discovered in the Federal Building hitched a ride to work from an employee's home.
"You have your purse next to your bed, or a bag. The bedbugs crawl into the bag, you carry it and have bedbugs at work," Gummow said.
It's never easy finding bedbugs, and Gummow said that because office chairs are perfect hiding spaces for the insects, finding them in a large office building can be even more difficult.
An IRS employee anonymously complained about seeing another bedbug several weeks ago, but agency officials say no more bugs have been found at the office.
They say they'll continue to monitor the situation.