He tells people he's there to spray and that they need to leave their apartments for two hours.
That's when he steals from them.
Police say he's struck five times this year, and four of those times have been in the past three weeks.
Police released a sketch of the man they are looking for.
Victim Leora Handlarsky remembers his face.
"He basically said he was investigating bed bugs," Handlarsky said.
When she returned to her bedroom, $5,000 worth of jewelry was gone.
"When I walked into my room, it was empty," Handlarsky said.
That is how the suspect operates, posing as an exterminator to enter apartments, then telling the tenants to leave because of the fumes. Then, he burglarizes the apartments.
One of the incidents happened in 2612 West 2nd Street, where management is sending out warning letters to tenants.
Police say the suspect is a black or Hispanic man, 28-35 years old, with a stocky build, thin mustache and wearing a dark colored uniform and carrying a canister.
"I feel a little stupid after the fact," Handlarsky said. "Hopefully we'll catch him."