The Northern Pencil-blue (Candalides gilberti) is a species of butterfly

Butterfly

A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 of the Lycaenidae

Lycaenidae

The Lycaenidae are the second-largest family of butterflies, with about 6000 species worldwide, whose members are also called gossamer-winged butterflies...

 family. It is found in the Northern Territory

Northern Territory

The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...

 and the north of Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

.

The wingspan

Wingspan

The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...

 is about 30 mm. Adults are blue. The underside of both sexes is white with rows of dark dots and dashes.

The larvae have been recorded feeding on Decaisnina signata and Alstonia actinophylla. They are narrow, green or red with various markings and have a length of about 15 mm. The colour depends on the part of the hostplant it is feeding on (it is green when feeding on the leaves and red when feeding on the flowers). Pupation takes place in a mottled brown pupa with a length of about 14 mm.