Insect of the Week: The Tobacco Hornworm

Adapted from pages 68-69 of Garden Insects of North America:

Tomato and tobacco hornworms spend the winter months in the pupal stage, within a chamber approximately 4–6 inches deep in the soil. Adult moths emerge in mid- to late spring and may migrate long distances. Their eggs resemble small pearls and are laid singly on foliage. The newly hatched caterpillars possess a horn that is nearly the same length as the body and subsequently pass through four to five additional larval instars over the course of about a month. Full-grown larvae burrow several inches into soil and create a cell in which pupation occurs.

Where these insects can successfully survive winter conditions there are typically two generations produced annually. The adults are very strong fliers and in more northern areas, incidence of tomato and tobacco hornworms from year to year may be strongly influenced by migrations of moths originating from more southerly areas.

An adult tobacco hornworm (Manduca sexta). Photo credit: John Capinera, University of Florida

Larvae develop into large caterpillars, with five pairs of prolegs and a flexible “horn” on the last segment. Most are generally green. Seven diagonal white stripes are present along the side of the tobacco hornworm, and the horn is usually red. Tomato hornworm has a series of V-shaped white markings along the sides, and the horn is often black. Less common dark green or even black forms of tomato hornworm may be present. Adults of both are strong-flying, heavy-bodied moths. The forewings may have a span of up to 5 inches and are generally gray or grayish brown with light wavy markings.

When it comes to hosts, tomatoes and tobacco are particularly susceptible to injury. Pepper, potato, and certain nightshade famil weeds are also hosts. Caterpillars chew leaves and can defoliate plants rapidly. Fruits, particularly green fruit, may also be chewed.

Garden Insects of North America: The Ultimate Guide to Backyard Bugs
Second Edition
By Whitney Cranshaw & David Shetlar

This second edition of Garden Insects of North America solidifies its place as the most comprehensive guide to the common insects, mites, and other “bugs” found in the backyards and gardens of the United States and Canada. Featuring 3,300 full-color photos and concise, detailed text, this fully revised book covers the hundreds of species of insects and mites associated with fruits and vegetables, shade trees and shrubs, flowers and ornamental plants, and turfgrass—from aphids and bumble bees to leafhoppers and mealybugs to woollybears and yellowjacket wasps—and much more. This new edition also provides a greatly expanded treatment of common pollinators and flower visitors, the natural enemies of garden pests, and the earthworms, insects, and other arthropods that help with decomposing plant matter in the garden.

Designed to help you easily identify what you find in the garden, the book is organized by where insects are most likely to be seen—on leaves, shoots, flowers, roots, or soil. Photos are included throughout the book, next to detailed descriptions of the insects and their associated plants.

An indispensable guide to the natural microcosm in our backyards, Garden Insects of North Americacontinues to be the definitive resource for amateur gardeners, insect lovers, and professional entomologists.

  • Revised and expanded edition covers most of the insects, mites, and other “bugs” one may find in yards or gardens in the United States and Canada—all in one handy volume
  • Features more than 3,300 full-color photos, more than twice the illustrations of the first edition
  • Concise, informative text organized to help you easily identify insects and the plant injuries that they may cause
This post is part of a series, explore additional posts hereInsect of the Week: the Snowy Tree Cricket >>