The Euproserpinus euterpe (the only common name being Kern Primrose sphinx moth, though most refer to the species by it's binomial) is a small day-flying moth in the Sphingidae (sphinx) family. The 0.04 inch, light green eggs are laid on evening primrose (Camissonia contorta epilobiodes ) and on filaree (Erodium cicutarium ). Larvae emerge from the eggs a few days after oviposition and begin to feed on the flowers and apical growth areas of the evening primrose. If eggs are laid on filaree, the larvae soon die because this plant does not nutritionally support them.

Early instar larvae (caterpillar phases ) are green with dark-brown to black heads, legs, lateral spiracles shields and blunt anal horns . Fourth and fifth instar larvae (i.e. caterpillars that have shed their skin 3 or 4 times) have red to dark red heads, green to red rust green bodies accented with black areas around spiracles, anal shield and anal horn. The legs are green and the prolegs (appendages that are not true legs) are red in these mature larvae. Adult moths have a gray ground color with patterned black and white markings on the forewings. Hindwings are gray to white with black marginal banding. Males are slightly smaller than the females and are difficult to distinguish. These are small sphinx moths with a wing span of 3 inches from tip to tip.

Adults nectar on a variety of flowering species that occur in the region, including, filaree, goldfields (Lasthenia chrysostoma ), Baby blue eyes (Nemophila menziesii) and miniature lupine (Lupinus bicolor ). The adult flight season occurs from the last week in February to the first week of April, with a peak period during the second and third week of March. This time may vary according to the climatic conditions in the region.

Distribution

Distribution is apparently restricted to a privately owned ranch in the Walker Basin , Kern County, California. This basin is an agricultural region , with grain and cattle the primary crops . The moth is found in cultivated barley fields or disturbed areas in association with its larval and adult food plants.

Conservation status

The occurrence of Erodium is a serious threat to the sphinx moth because of larval mortality after mistaken egg depositionby the mother. Until 1974 the species was considered to be extinct, at which time a surviving population was found in the eponymous Kern County. Sphinx moths are valuable to insect collectors, who may also pose a threat to this small population - seemingly wiping it out. The species has not been seen in nature since 1982. Pesticide or herbicide application could also endanger the moth. This species is extremely rare and in most years field surveys have found few or no individuals. However, desert Lepidoptera often show great natural variations in population size in response to climatic conditions, and surveys may more accurately reflect population status in years with above-normal rainfall.

References

• C. Thelander, Life on the edge: a guide to California's endangered natural resources. Edition 1994. BioSystem Books. Santa Cruz, California. p 442-443.
• P.M. Tukes and J.F. Emmel. The life history and behavior of Euproserpinus euterpe (Sphingidae). 1981. Journal of the Lepidoptera Society 35:27-33.
• U.C. Berkeley, Essig Museum of Entomology. California's Endangered Insects'
• U.S. Fish and Wildlife Service. Kern Primrose Sphinx Moth Recovery Plan. 1984. Portland, Oregon.