Another wasp that I have not seen before.
A platoon of about 6 of them show up today.
Overall size is approx 30mm in length.

Sphex sericeus 黃色穴蜂 Male

ID Credit : Christophe @ hkwildlife forum

Reference
http://www.hkwildlife.net/Forum/viewthread.php?tid=89085&page=1&extra=#pid375619

+++++++

Wrong ID :
The patterns on abdomen is similar to 毛斑鋸泥蜂 Prionyx viduatus (Christ, 1791) but the size doesn't match the information in Taiwan gaga website.

Reference :
http://www.zobodat.at/pdf/LBB_0047_2_1581-1599.pdf
http://blog.xuite.net/r0123401234/twblog/119956454-毛斑鋸泥蜂
http://gaga.biodiv.tw/9912bx/798.htm