[2] The adult is on the wing in June and July (this refers to the British Isles; other parts of the range may differ) and both sexes are moderately attracted to light.

The adult moths spend most of the 24 hours resting, in a wide variety of places from the tree canopy to the base of the ground vegetation.

A number of males gather in one limited space and start to display, alternating between perching on the vegetation with their wings spread out, or flying rapidly in a figure of 8 pattern which is so quick that the human eye interprets it as a “pendulum” motion.

The males prominently dangle their modified hindlegs, which end in yellow brushes that disperse an attractive scent, or pheromone.

[11] The pupa stage is short and takes place in May or early June in leaf litter or moss, in a thin cocoon covered in soil or plant remains.

[11] Previously placed in the genus Hepialus – from the Greek; hēpialos – meaning a fever, as in 'the fitful, alternating flight' of the moth.

[clarification needed] The specific name hecta is from the Greek hectikos – feverish or hectic; from either the flushed forewing or the moths flight, or both.