The mandibles are usually lost, the labrum is reduced to a narrow transverse sclerite, and the labium is a small flap ( though its palps retain quite large).

上颚消失，上唇退条窄横片，唇退小片（唇须发达）。

The experiment is such: Researcher uses foam rubber or plastic from the female alar collect secretion, dissolve is in at the inunction after alcohol the labrum of a few females.

研究人员用海绵从收集分泌物，溶于酒精后涂擦在些的上唇。