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Past Articles Library | Organic Pest Control | Tomato Hornworm

TOMATO HORNWORM
(Manduca quinquemaculata)

Tomato hornworms are large caterpillars in their larvae stage, that blend very well with foliage, and can do serious damage to leaves. They are found throughout North America.

DESCRIPTION

Adults are mottled gray, narrow winged moths with 4-5 inch (10-13 cm) wingspans and rows of orange dots along their thick, furry abdomen. At dusk they feed on nectar from flowers. The green larvae are up to 4-1/2 inches (11.4 cm) long with a single large horn on their tail and with diagonal white marks along their sides. Their eggs are round and yellowish green.

LIFE CYCLE

The large, dark brown pupae overwinter in the soil, and the moths will emerge in June and July. Females lay their eggs singly on the undersides of leaves; eggs will hatch in a week. Larvae feed for 3-4 weeks, then pupate in the soil. Usually there is only one generation per year, two or more generations where it is warmer.

PLANTS MOST AFFECTED

Eggplant, pepper, potato, tobacco, and tomato.

DAMAGE

Larvae chew large holes in leaves and may completely strip young plants. In severe infestations, larvae also feed on stems and chew large holes in the fruit.

MEANS OF CONTROL

• You can handpick the caterpillars from the foliage
  
  
• Spray Bacillus thuringiensis (Dipel) while caterpillars are still small. Read more about how and when to use Dipel - Dipel For Chewing Caterpillars
  
  
• Till the soil in the fall or early spring to destroy any pupae
  
  
• You can try growing nectar or pollen plants to attract native parasitic wasps, which usually provide some control in most areas
  
  
• Release lady beetles or lacewings to attack the eggs