It is cross border terrorism of a different kind, but an equally dangerous one. Scientists at the Arid Forest Research Institute in Jodhpur blame the insect, Derolus Discicollis, first traced to Sindh in Pakistan over a century ago, for destroying thousands of evergreen, life sustaining Khejri trees in six desert districts of Nagaur, Churu, Sikar, Jhunjhunu, Bikaner and Barmer.