There are four widespread species of Achaea here which are very similar & can be pest.
They are A. janata, serva eusciasta, & mercatoria.

By comparing the cats of A. janata & serva , these two are very unlikely & can be ruled out.
http://lepidoptera.butterflyhouse.co...to/janata.html
http://lepidoptera.butterflyhouse.co...ato/serva.html

The adult of A. mercatoria can be recognised by the falcate forewing tip.
http://www.africanmoths.com/images/E...ria1%20upp.jpg

This leaves Achaea eusciasta .

TL Seow