To determine the larval grease content in each sample, the extraction of grease was accomplished by a previously reported method with some modification [16]. A classical Soxhlet system with cellulose extraction cartridges was employed. Instead of refluxing extraction for 16 h, petroleum ether (200 ml) extraction was conducted twice for 8 h in Soxhlet extractor. Crude grease was obtained by combining the leaching liquor and evaporating petroleum ether with a rotary evaporator, and then the crude grease was calculated by weight.