labrum

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，上唇退化为一条窄横片，唇退化为一小片（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.

研究人员用女性腋收集分，于酒精后涂擦在一些女性的上唇。