Battus philenor hirsuta Male Ecloses

A Battus philenor hirsuta (California pipevine swallowtail) male eclosed today after diapause.

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Pipevine swallowtails have one of the strangest flight times among Californian butterflies. Being a member of the tropical Triodini tribe, everything about the species is just. . .well, tropical. Unlike temperate species that register temperature and photoperiod changes to time diapause and eclosion, tropical species typically register humidity changes instead. The pipevine swallowtail still seems to retain tropical traits from its ancestors despite being in a temperate climate, and thus its ecloses and enters diapause in a rather erratic fashion. In any given brood of this species, some members will eclose in a few weeks, others will enter diapause and eclose in a few months, and the remainder will diapause until the following spring. Thus, the chrysalises produced from the larvae we reared last summer eclosed randomly throughout the year. They finally stopped eclosing for the past few months, but recently we have begun spraying all our diapausing butterfly pupae which triggered this male and possibly others to break diapause and eclose. The timing of the eclosion is actually fairly accurate despite that the chrysalises were kept indoors, as the flight of the wild population should be beginning now. Maybe we'll go release this individual back in the mountains were it was found this weekend.

Battus philenor hirsuta is sexually dimorphic, with the iridescent blue and green on the hindwings being a characteristic of the male. The females are mostly grey and only have the blue on the forewings. Pipevine swallowtails may not look as showy as some of the other yellow swallowtails, but when the light is shining on the wings at the right angle, they gleam and reveal their colors making them quite stunning. 

Update 3/18: well, here's another photo posed on a lilac blossom, a classic swallowtail nectar flower.

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Authors
Alan Liang