This hawk moth caterpillar was found on the leaf of Seaside Clerodendrum (Volkameria inermis) in December 2010. The other potential hostplant is Thai Pea Eggplant (Solanum torvum). There is another species reported in Singapore, Acherontia lachesis. Apparently, the hostplant of this species is the Seaside Clerodendrum although it also feed on Blue Snakeweed (Stachytarpheta indica). Hence, the caterpillar that I saw may be Acherontia lachesis instead.

References:

Leong TM, Tay A. Final instar caterpillar and metamorphosis of Acherontia styx medusa Moore, 1858 in Singapore (Lepidoptera: Sphingidae: Sphinginae: Acherontiini). Nature in Singapore 2011;4:13-18. | Read article |

Leong TM, D'Rozario V. Final instar caterpillars and metamorphosis of Acherontia lachesis (Fabricius, 1798) in Singapore (Lepidoptera: Sphingidae: Sphinginae: Acherontiini). Nature in Singapore 2011;4:101-114. | Read article |

Leong TM. The brown form final instar caterpillar of the hawkmoth, Acherontia lachesis (Fabricius, 1798) in Singapore (Lepidoptera: Sphingidae), with an account of parasitism by the tachinid fly, Drino (Zygobothria) atropivora (Robineau-Desvoidy, 1830). Nature in Singapore 2011;4:251-258. | Read article |