This caterpillar was identified as a member of the Sphingidae family. These caterpillars lose their horns in the last instar prior to pupating. At this time they also change color as is seen with the caterpillar pictured above.

About 1100 species of these moths are found around the world. The moths feed on nectar of many plants in late afternoon. The adult moths are mostly medium to large in size, and are sometimes referred to as hawk moths or hummingbird moths because of their rapid wing beats and hummingbird appearance. The larval stage (caterpillars) are known as hornworms and feed on many different plants.

In the fall these large caterpillars can often be found crawling in the grass and among the plants in flower and shrub beds. At that time of year these caterpillars have completed their feeding period and are searching for a suitable place to pupate and over-winter. Most of the caterpillars are rather large, some three to four inches long, some shade of green in the early stages, with oblique stripes along the sides and an appendage resembling a horn on one of the abdominal (eighth) segments. Their habit of assuming grotesque attitudes suggests an Egyptian sphinx and accounts for the family name Sphingidae. They pupate in the soil (in silk-lined cells) or in litter.

Common members of this family include the Tobacco Hornworm [Manduca (Protoparce) sexta], the Catalpa sphinx [Ceratomia catalpae], and the tomato hornworm [Manduca(Protoparce) quinquemaculata].

This hornworm is common on Oenothera fruiticosa cv. `youngii', the `Young Sundrops Evening Primrose'

References used:

Arnett, R.H. 1997. American Insects: A Handbook of the Insects of American North of Mexico. The Sandhill Crane Press, Inc., Gainesville, Florida.
Carr, A. 1979. Rodale's Color Handbook of Garden Insects. Rodale Press, Emmaus, PA.
Chu, H.F. 1949. How to Know The Immature Insects. Wm. C. Brown Company, Publishers. Dubugue, Iowa
Cranshaw, W. 1992. Pests of the West. Fulcrum Publishing, Golden, CO.
Peterson, A. 1962. Larvae of Insects: An introduction to Nearctic Species. Part I - Lepidoptera and Plant Infesting Hymenoptera. Edwards Brothers, Inc. Ann Arbor, MI.
Swan, L.A. & C.S. Papp. 1972. The Common Insects of North America. Harper & Row Publishers