Forest Pests: Insects, Diseases & Other Damage Agents

Hornworms (Family Sphingidae)

Maier, C.T., C.R. Lemmon, J.M. Fengler, D.F. Schweitzer, and R.C. Reardon. 2004. Caterpillars on the Foliage of Conifers in the Northeastern United States. FHTET-2004-1. Morgantown, WV: USDA Forest Service, Forest Health Technology Enterprise Team; 151 p.

The caterpillars of this moderate-sized family are medium to large, usually 25 to 90 mm in length at maturity. They typically have a prominent middorsal horn or sometimes a button on A8. The pine-feeding species of Lapara lack the horn. The hornworms typically have six to eight shallow creases around each segment. They have five pairs of prolegs, with the last pair flattened to form a triangular area below the anal plate. The crochets of two lengths are aligned parallel to the body axis. Most of the species are hairless except near the prolegs.

The hornworms eat the leaves of trees, shrubs, or herbaceous plants. They often reveal their presence by causing extensive foliar damage or by producing large frass. Because of their large size, conspicuous horn, oblique lines, and large frass, the tomato hornworm, Manduca quinquemaculata, and the tobacco hornworm, M. sexta, are familiar to most gardeners.

The moths have narrow forewings that, in most species, are two to three times longer than wide. Most have long mouthparts that allow them to reach deep into a flower to drink nectar. The adults, which are known as hawk or sphinx moths, fly like hummingbirds and are active during the night or the day, depending on the species. Many fly at dusk to visit flowers. Lapara species fly at night, and they do not feed.

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