MUNHALL, Pa. (AP) — Bed bugs have forced a school district in Allegheny County to close. The Steel Valley School District in Munhall is keeping students and staff home today in order to treat and clean all its buildings. In a letter to parents on Tuesday, Superintendent Edward Wehrer wrote a suspected bed bug was found in a high school classroom on Monday and in a middle school student’s book bag on Tuesday. The district expects to reopen on Thursday.