When I saw this lone caterpillar in April 2014 on my way to the Tree Top Walk, I did not know exactly which species of butterfly it belongs, though I know it was likely to be a member of the Swallowtail Family (Papilioninae). The caterpillar was found on a Pink Wampee (Clausena excavata), which belongs to the family Rutaceae. I went to the Butterfly Circle host plant checklist but the plant was not listed.
The case was shelved until February 2015 when I came across a butterfly laying eggs on a Pink Wampee in a park. A total of 2 tiny yellowish eggs were laid on two separate young leaves. I also managed to snap a picture of the butterfly in flight (though blurry).
As the leaves of Pink Wampee looks very similar to that of the India Curry Tree (Murraya koenigii), the identity of the host plant might be missed or confused. Indeed, Murraya koenigii is listed in the Butterfly Circle host plant checklist in relation to this butterfly. The only website that I found that listed Pink Wampee as the host plant of this butterfly was Butterfly Corner.