ARTHROPOD MUSEUM NOTES
Number 67 • August 3, 2009 • Jeffrey K. Barnes
Carolina sphinx, tobacco hornworm
Genus and species: Manduca sexta (Linnaeus)
Tobacco hornworms, larvae of Carolina sphinx moths, are pests that often defoliate tomato plants and damage tomato fruit in Arkansas gardens. They are also found feeding on potato, tobacco, and other plants of the nightshade family Solanaceae. The mature yellowish green hornworm has seven white, oblique, lateral lines on each side, and its caudal horn is orange to red. In contrast, the closely related tomato hornworm, Manduca quinquemaculata (Haworth), caterpillar of the five-spotted hawkmoth, has eight white, lateral, forward-pointed V-shaped chevrons on each side and a blue to black caudal horn. Both species occur from southern Canada south to Florida and Texas, causing similar damage to garden plants, but the tomato hornworm is relatively uncommon through much of the Southeast. Both species are present throughout Arkansas and may be found damaging the same plant. Mature larvae burrow into soil and transform into pupae with characteristic mouthpart loops often called jug handles. Adults imbibe nectar and are often seen hovering near flowers at dusk. They deposit small, spherical eggs principally on the underside of leaves of the host plants. Damage from young larvae often escapes notice, but in their last instar the caterpillars consume large amounts of foliage and the damage is readily evident. A quick search of the damaged plants will often reveal the culprits.