Yellow and Black Carpenter Bee (Xylocopa aestuans) (?)
Seletar West, 4th October 2013

Older sources refer to Xylocopa confusa, a name that is actually a junior synonym for Xylocopa aestuans. Confusingly enough, females of another species of carpenter bee, Xylocopa nigroflavescens, appear nearly identical to those of Xylocopa aestuans except for some minor differences in external morphology. Both species occur in Singapore, and it is difficult to differentiate females of Xylocopa aestuans from Xylocopa nigroflavescens in the field. On the other hand, the males are more readily distinguished.