Fifty grams of sample were placed in the box and adult insects were added to the sample. The conveyor was switched on and ensured that it was running at its maximum speed. The power was adjusted to the desired level. The grain, along with the insects, was then kept on the conveyor belt and the sample was subjected to microwave energy. When the box came out of the conveyor it was gently taken out and the sample was spread on a sheet of paper. The numbers of alive and dead insects were counted. The adult insects were considered dead if they failed to respond to gentle rubbing with a small brush. The sample was allowed to cool and the insects were checked for mortality again after 15 min. When the number of insects observed was not 100%, the same experiment was repeated until 100% recovery was achieved. Three replicates were done for all the mortality experiments.