Hornworm
(Manduca quinquemaculata)

Overview

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The species Manduca quinquemaculata is normally known as the hornworm and is a common pest to tomato plants. Although this species rarely reaches the infestation level required to cause economic damage, the potential is still there, mainly because this can be a periodical pest able to literally “explode” its population in a crop, under favourable conditions. Though the tomato is the main plant affected by this species, the young larvae are also known to infest eggplant, pepper and potatoes. If present, control must target small larvae. 

Main description

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The eggs of M. quinquemaculata are deposited singularly on both surfaces of the leaves in late spring, which are light green to yellow in colour. The larvae are pale green in colour with white and black markings. The first instar is yellowish white in color with no markings. Later instars are big (8-12 cm or more) and develop eight white, lateral "V-shaped" marks. A black projection or "horn" on the last abdominal segment gives the caterpillar the greatest distinction and the name hornworm (typical of the Sphingidae family).

Scouting

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The current action threshold for tomato hornworm is very low, corresponding to 0.3 to 0.5 young-small larvae per plant (one larva per 2-3 plants). If this larval density is exceeded, insecticide treatment is recommended.