Hiscox, the specialist insurer, has estimated the cost of the April and May tornadoes in the US at around £35m.This comes on top of estimates for the Japan earthquake of between $60m (£37.6m) and $150m.Including other catastrophes such as the New Zealand earthquake, total reserves for pay outs have hit £200m compared to £100m at the equivalent stage last year.In its trading statement, however, Hiscox points out that heightened awareness of catastrophes has seen a 10% increase in reinsurance in the US.BS