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.

研究人员用海绵从女收集分泌物，溶于酒精后擦在一些女的上唇。

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，上唇退化为一条窄横片，唇退化为一小片（唇须发达）。