It occurs in granite sand plains and gravel field habitat and has been collected in early February.

[3] This species is visually similar to its close relatives Hierodoris frigida, H. polita and H.

[3] It has a white-scaled surface to its exterior labial palpi and does not have the transverse white forewing fascia of H.

[3] It has been hypothesised that this feature enables the females to lay eggs beneath the surface of the sand close to host plant roots.

[3] H. extensilis has been classified as having the "At Risk, Naturally Uncommon" conservation status under the New Zealand Threat Classification System.