This is Lymantria sinica (identified as L. nebulosa in my thesis), as noted in Pogue & Schafer (2007).
Please also note that Lymantria serva is no longer a correct name (I also used this name in my thesis). Pogue & Schafer (2007) note that the correct name of Lymantria iris Strand, 1911 was taken out of synonymy with L. serva by Schintlemeister in 2004.
Hong Kong is the type locality of L. iris.
Pogue, M.G. & Schaefer, P.W., 2007. A review of selected species of Lymantria Hübner  (Lepidoptera: Noctuidae: Lymantriinae) from subtropical and temperate regions of Asia, including the descriptions of three new species, some potentially invasive to North America. Forest Health Technology Enterprise Team (USDA Forest Service), Washington D.C., USA. 223 pp.
[ Last edited by hkmoths at 2008-8-12 08:42 ]