Paralecanium expansum metallicum lives in forested tropical environments in south-east Asia.
In forests, the metallic females may resemble splashes of sunlight filtering through the canopy, perhaps explaining how this feature has evolved.
It, and other members of the genus Paralecanium, seems to prefer feeding on the upper surfaces of leaves.
P. expansum metallicum develops in small colonies on the upper surfaces of the leaves of its hosts, whereas most other phytophagous bugs take advantage of the shelter afforded under the leaves.
The presence of the adult female is betrayed by a silver-metallic sheen, almost certainly a form of iridescence. The living insect appears like a splash of metal solder on the leaf.
While scale insects are generally regarded as pests, many are actually specially adapted to natural habitats and so habitat conservation is an issue. P. expansum metallicum is likely to be at risk from habitat loss.