The head pattern and diagonal stripe appear to be at variance with a D. solomonensis larva. But late instar Erebus terminitincta has a diagonal stripe and a tail wart, although the general pattern does not match this specimen.
I am not sure it is Sphingidae. Nearly all of them have single 'tails' and the anal claspers tend to look different - more under the body, not sticking out backwards. Not found an alternative ID but in a couple of references my eye was drawn to this species. It IS NOT IT but has many similar features http://lepidoptera.butterflyhouse.com.au/ereb/solomonensis.html
