DISTRIBUTION: The Yam Hawk Moth, Theretra nessus (Wing span: 90-130mm) flies in Japan and the Indo-Australian tropics (India, Philippines, north-east quarter of Australia) to New Caledonia. This species was introduced to Hawaii. "The broad irregular yellow band of the hindwing, the yellow-flanked, green abdomen and the green costal zone of the forewing interacting irregularly with the pale postmedial band distinguish this species." Image courtesy of Tony Pittaway.

FLIGHT TIMES AND FOOD PLANTS:

Moths probably start spring flight in April-May and continue until September. The adults come readily to lights and nectar at various flowers.

ECLOSION:

Pupae wiggle to the surface just prior to eclosion.

SCENTING AND MATING:

Females extend a scent gland from the posterior tip of the abdomen. The gland releases a pheromone into the night sky. Males fly into the wind and detect the pheromone plue with their antennae.

EGGS, LARVAE, PUPA:

Larvae are regarded as agricultural pests, feeding on Yam ( Dioscorea discolor, DIOSCOREACEAE ), and Cunjevoi ( Alocasia macrorrhizos, ARACAEAE ). Larva also feed on Amaranthus, Impatiens, Citrullus, Arachis, Boerhavia, Knoxia, Morinda, Oldenlandia, Spermacoce, Glossostigma and Camellia.

"Mature larvae attain lengths of 90-120mm. There are both green and dark (yellowish brown) forms with white dorsolateral and (green form only) dorsal lines. The ocellus on A1 is obliquely oval, white, edged with blue to the interior; a much smaller ocellus occurs within the dorsolateral stripe on A2. All abdominal segments in the brown form have triangular blue patches to the dorsal side of the dorsolateral stripe. Oblique bars occur laterally from A2 backwards, white in the green form and darker brown in the brown form."

Theretra nessus on a potato vine (Dioscorea batatas),
Kaneohe, Hawaii, courtesy of John M. Flanigan

Sphingidae of Hawaii

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Theretra nessus