Very small beetle
5mm in length.

橫帶毛皮蠹 Attagenus fasciatus(Thunberg, 1795) Dejean, 1837
(Coleoptera: Dermestidae)
see also:

ID Credit : nadia @ hkwildlife forum

Reference :
http://www.hkwildlife.net/Forum/viewthread.php?tid=87827
http://www.dermestidae.com/Attagenusfasciatus.html
http://www.fehd.gov.hk/english/safefood/photo_page2/Dermestidae/Attagenus%20fasciatus.html