Worcester-based Hanover Insurance Group, Inc. estimates its second quarter earnings will drop from $70 to $77 million before taxes due to domestic catastrophe-related activity.

Catastrophe losses during the quarter were primarily related to severe hail and wind storms from 11 events in the U.S. The largest losses were caused by hailstorms in the Midwest in April and a series of widespread hail and windstorm events in the Midwest and Mid-Atlantic regions in May and June. Second quarter results are also expected to be impacted by additions to reserves in certain domestic lines, primarily in surety and auto. Surety reserve additions are driven by continuing weak economic conditions, while auto reserve re-estimations primarily reflect an increase in severity of losses from the 2011 accident year.

Taking this into account, as well as other currently available information, The Hanover expects second quarter segment income after tax per share to be in the range of $0.15 to $0.25.

"Catastrophe activity in the U.S. continues to impact industry results as well as our own," said Frederick H. Eppinger, chief executive officer at The Hanover, in a statement. "However, the strategic diversification of our business is helping us mitigate the volatility associated with weather. Higher than expected catastrophe losses in our domestic operations were somewhat offset this quarter by lower catastrophes in our international business. Perhaps most importantly, we are satisfied with our accident year results, and we continue to see favorable pricing and retention trends."