The on demand routing protocols for mobile ad hoc networks use network-wide broadcasts of control packets to learn routes. This feature can be exploited by malicious nodes to launch highly leveraged denial of service attacks in ad hoc networks. We use an adaptive statistical packet dropping mechanism to mitigate such attacks and their impact on throughput. The proposed mechanism does not use any additional network bandwidth. Using experiments on a wireless testbed, we evaluate the effectiveness of the statistical technique for UDP and TCP traffic.