For the third time in six months, a team of exterminators on Monday visited the state’s Welcome Arnold shelter in Cranston in an attempt to eradicate a persistent bedbug problem that has been plaguing the shelter’s homeless residents.

The bedbug infestation had emerged as one of the chief complaints of a group of 70 shelter residents and other housing advocates who marched to the State House last week in an attempt to get the attention of Governor Carcieri and get him to do something about the conditions at Welcome Arnold.

At that session, Noreen Shawcross, the state’s chief of housing and community development, and Clark Greene, the governor’s chief policy aide, promised the People to End Homelessness that a team of exterminators would be at the site as early as Monday. Also promised were new mattress covers to make the mattresses “bedbug proof.”

Dennis M. Langley, the executive director of the Urban League of Rhode Island, the agency contracted by the state to oversee the operation of the shelter on a day-to-day basis, said he believes that the exterminators did what was asked, but “I would not be telling the truth if I said it has been completely solved. This is a difficult group of insects to get rid of.”

In anticipation of Monday’s fumigation, residents were strongly encouraged by shelter staff to wash and clean all their belongings and to deposit them in special bags that would be kept at the shelter during the day to keep them from being infested with new insects picked up from the outside.

That policy appeared to work, said Langley, though he acknowledged that the shelter the following day reinstituted the practice of requiring residents to take their belongings with them when they left for the day. “We just don’t have the room to store the belongings of 117 residents.”

Langley said that in keeping with another promise to the homeless residents, the shelter has purchased 100 used mattresses to replace those that are cracked or that have stuffing falling out. Twenty-six mattresses, acquired from the Donation Exchange, were installed yesterday, and 75 others, purchased from a nursing home, should arrive soon, he said. Some 250 mattress covers have been purchased but have not arrived.

According to state officials, the Welcome Arnold is due to be closed in the next several months but not before a new shelter site has been found. The governor’s staff was originally considering using the Summit Nursing Center off North Main Street, but is now looking at property on the grounds of the John O. Pastore Center in Cranston.

At the meeting with the governor’s staff, the homeless advocates said they preferred that the state not build another large shelter but rather finance transitional housing in smaller apartments.

But Langley, whose agency runs a small shelter for 12 women on Chester Avenue, said he has run into many homeless people who say they don’t want a smaller apartment and feel safer in a larger building with a dormitory setting.