Platinum Underwriters Holdings Ltd expects to take a hit of $74.8 million from catastrophes in the second quarter of 2011 and increases from its first quarter loss estimates.The insurer estimates losses of $28 million from the severe weather in the US in April and May and a total of $46.8 million in first quarter loss increases, including $32.9 million from the New Zealand earthquake in February, $7.2 million from the Japanese earthquake and $6.7 million from the 2011 Australian floods and Cyclone Yasi.The company added that it believed the New Zealand earthquakes last month would result in less than $10 million in losses and therefore would be incorporated into its attritional loss ratio.Argo Group International Holdings Ltd also announced loss estimates of $30 million to $35 million for the second quarter as a result of the US storms.