Yellow-banded Carpenter Bee

Description:

Apidae; Xylocopinae; Xylocopiti; Xylocopini; Xylocopa; Xylocopa philippinensis Smith, 1954. This large bee, as its name suggests, is endemic to the Philippines. The common name "Yellow-banded Carpenter Bee" leads me to think that all X. philippinensis have yellow bands, but that does not seem to be the case, unless I am misunderstanding something. Wikipedia's article has a lengthy section called "Characteristics" which goes into some detail about the confusion that exists concerning the presence or absence of yellow bands, but X. philippinensis is not specifically mentioned. I can only say that every time I see these large black bees, I always notice that some have yellow bands and others do not. It may be a simple case of sexual dimorphism, or it could be that I am looking at different species. When I checked some of my older notes, this is the reason why I refrained from sending any of my previous spottings to Project Noah. I just was not sure of what was in my photos. If anyone can clarify this for me, I would be grateful.

Habitat:

Spotted visiting unidentified yellow flowers at the side of a farm road.

Notes:

As you can see, my first and second photos show yellow bands. The third and fourth (two pictures of the same bee) do not show the yellow bands. I have been unable to find any information to explain this.