At 4:30 a.m. last Wednesday, bedbugs chased Jessica Wolf and her three children out of their St. Cloud apartment. As if that weren't enough trouble, the landlord told Wolf that the blood-eating insects were her guests, so she had to pay to evict them.

The rapid spread of bedbugs and their tenacious infestations have led to new tensions between landlords and tenants. Since 2007, HOME Line, a tenant rights hotline based in Minneapolis, has received 626 bedbug calls, including 272 so far this year. The issue is almost always about the tenant getting billed for the spraying or costly heat treatment that's used to eradicate the pests.

One of the callers was a Lakeville woman who is facing eviction because she hasn't paid a $1,147 bill from her landlord for bedbug treatments in her unit.

"More than any other topic I've ever seen, landlords want to blame tenants for bedbugs," said Mike Vraa, managing attorney at HOME Line. In Vraa's view, state law allows landlords to do that only if they can prove the bugs moved in because of the tenants' "willful, malicious, or irresponsible" conduct.

Some landlords and their advocates are using a different standard, whether invoking the language in leases or the opinions of pest control companies about where the infestation likely originated. Yet most agree that bedbugs are showing up in so many places that their presence is more a result of someone's bad luck than negligence.

"We can get them anywhere and everywhere now," said Robyn Frederick, an associate certified entomologist with Godfathers Exterminating in St. Cloud.

Wolf, 31, works at McDonald's and moved into her $530-per-month apartment seven months ago. In the late summer, she noticed a rash on her 3-year-old and took him to the doctor, who recommended she change her detergent. Then earlier this month, she was taking off her bedding when she saw a single bug on the mattress. She kept looking and saw seven more, from a tiny baby to full-grown bedbug that was "a little bit bigger than a tick."

Shaken, Wolf called her landlord, David Puchalla, who sent out an exterminator to spray. Puchalla accused her of inviting the bugs into his property by bringing in a used mattress and said she would have to pay at least $300 for the spraying.

"I've never had bedbugs in that building. She's the first," Puchalla said Wednesday. "When your children get head lice at school, do you come and ask me to pay for the treatment?"

Wolf complained to the St. Cloud health department. An inspector issued an order last week to Puchalla to wipe out the bedbugs, pronto.

"It's darned near impossible to find out who brought bedbugs into an apartment," said Lisa Schreifels, the St. Cloud health director.

Last week, the bedbugs so creeped out Wolf that she couldn't sleep. One night, she spotted the bugs crawling up the wall. Wolf pulled her children out of bed and took refuge at her mother's house.

On Friday, Puchalla had changed his opinion on the origin of the infestation. Late last week, an exterminator found eight bedbugs in a different unit, and only one in Wolf's apartment. Puchalla now thinks the bugs came from the other tenant's unit.

The exterminator will return Monday and use the most effective bedbug killer: heating the infested areas to 120 degrees or more. Puchalla said he hasn't decided who will pay the bill.

"The bottom line is, this building's going to be clean," he said.

After the insects showed up in Ann Fuller's home last spring, her landlord -- the Dakota County Community Development Agency -- paid an exterminator to banish the bugs from her Lakeville apartment. Fuller and her 12-year-old son could soon follow them, as she faces an eviction hearing next week for failure to pay the exterminator bill for her unit.

While two adjacent units were treated at no cost to the tenants, the agency decided to charge Fuller because the exterminator determined the infestation began in her unit, said Sara Swenson, a spokeswoman for the Dakota County CDA. The lease requires tenants to "keep the premises in such condition as to prevent health or sanitation problems from arising," and to reimburse the landlord for fixing damage to the premises.

Swenson said Fuller had the option of paying about $53 extra each month for two years, but she declined.

"I just don't think it's fair," Fuller said.

With bedbugs hitching rides in everything from luggage to laundry, some say landlords can do more harm than good by trying to bill tenants for bedbug treatments.

Donna Hanbery, a Minneapolis lawyer who represents property managers, said she doesn't believe that any single law is "determinative" about who's responsible for bedbug treatments. But she advises landlords to do everything they can to encourage tenants to notify them immediately about a bedbug foothold.

"If you make it about money, you're going to have people ... hiding it," Hanbery said.