Bror Hanson's 'About Hepialus hecta' (1938): a pioneering study of moth behaviour (Lepidoptera, Hepialidae)

Hanson's (1938) atmospheric narrative of the mating behaviour of Phymatopus hecta is reprinted in a new translation from the Swedish. The paper is a classic of focussed investigation within a century in which only fragmentary information about this species was published; regrettably it remained unnoticed for forty years. Hanson established that the courtship behaviour was non-stereotypic (each of his three observed courtships was unique), and that both males and females could attract each other. He suggested that the males were deploying a pheromone, noted an extraordinary back to front copulation procedure, and was the first to report predation by wasps. All of which waited from half to three-quarters of a century before being reconfirmed. Some of his detailed observations are ambivalent, being at variance with recent observations in Scotland, suggesting either that the populations have diverged, or that the behaviour was locally modified because of a highly distorted sex ratio. Or he may simply have been inaccurate in distinguishing males from females. The reported timing of events suggests, using the time of sunset, that the observations were made in the region of Kalmar and Öland in south-eastern Sweden; there is a strong suggestion that the period of activity is shifted to a time more in advance of sunset, relative to the Scottish populations.