The consumer price index increased a seasonally adjusted 0.2% in May from the prior month, the Labor Department said Thursday. It had risen 0.4% in April and 0.1% in March.Excluding the volatile categories of food and energy, the so called core CPI, consumer prices rose 0.2% in May as well. Consensus had expected a 0.3% gain for overall prices and a 0.2% increase in core CPI. From a year earlier CPI rose 1.0%, down from 1.1% in April. Core prices climbed 2.2% on the year, matching expectations.