Grateful if you would have a look at the image of this caterpillar. I am presuming it is a Papilio species. It's commonly found on citrus but does not seem to do a lot of harm, although it can be a nuisance on seedlings. I could not find good matches on the Internet, although there are Australian species (eg P. aegeus), but none seemed to have the same red tentacles as in my image.
Also, If you have an image of an adult and would like to share it for a fact sheet, please let me know.
I agree it is most likely a Papillio spp. In the Solomons there are seven species of Papillio, the most common being bridgiei, fuscus and woodfordi. I believe they all have the horns in the front which only appear when provoked, i.e. in defense. I have never seen them causing serious damage except to individual trees in a garden, they are always well parasitised. Sorry I don't have a pic of the adult.
To id your adult try using
It is an excellent source of pictures and data. I have a copy but it is in Gizo and i am in Wellington.
I took that photo (Citrus caterpillar - Melanesia) in Takwa, Malaita, Solomon Islands, and had identified it as Papilio aegeus, but it may be more likely to be another species within that genus.
I'm adding here another photo I took of younger larvae belonging to the same genus in Subobono, Malaita on 29 October 2005.
Sorry I don't appear to have any photos of adults.
This photo, from Guadalcanal, is likely the female of a species of Papilio.
I'm seeing if I can identify it further, but it has been wrongly attributed to Ornithoptera victoriae in the photos of pests of Solomon Islands database we began compiling all those years ago.
According to Coffs Harbour butterfly house Palullio fuscus larvae feed on various members of the RUTACEAE plant family including some Australian natives. Wikipeadia has similar lists for other species of Papillio.
and the introduced :