Oleander Hawk Moth Caterpillar

Description:

Green caterpillar found on plant with small white flowers. There were four of these on this plant. In front of the building I live in. These fellars were eating and stripping off the leaves of the plant pretty good. Just a guess but perhaps some sort of Sawfly Caterpillar? Doing some looking around, I believe the plant the caterpillars are on is a Madagascar Rosy Periwinkle plant, and possibly, the caterpillars are Hawk Moth caterpillars, perhaps specifically Oleander Hawk Moth caterpillars. I occasionally see Hawk Moths in this building at night (Open-air building)

Habitat:

An area with lots of gardens around

Notes:

Correction. These caterpillars were not on a Pink Bell plant. Plant was originally misidentified. The actual name of the plant the caterpillars are on is yet unidentified. Identified 9/7/2015 from the moths that emerged from the pupa stage under the plant these caterpillars were on, which indeed was a Madagascar Rosy Periwinkle plant.