Page 42 - AG 7-2011 Revised 2016

Tomato Sphinx Moth adult Tobacco Hornworm

Photo Courtesy of UNIVAR Photo Courtesy of UNIVAR

1.Antenna-2 segmented 6.Thorax-mesothorax w/greenish and white strips Hornworm

2.Eyes- ocelli numerous 7.Petiole-none 3 10
8
3.Head-head capsule 8.Abdomen- 8 segments

4.Legs-3 thoracic legs 4 pro legs 9.Color-various colors of green

5.Wings-adults only 10.Other-anal horn present on tomato

hornworm

Life Cycle
Hornworm eggs are laid on leaves. The larvae hatch and feed for 3 or 4 weeks,

then burrow into the soil to pupate. The adult Tobacco or Tomato moth is a 4 4

good flier, with a wingspan up to 5 inches. The life cycle can take only about “3 Thoracic” “4 Prolegs”

2 months in summer, with the larvae most common in midsummer. Winter is

passed in the pupal stage. There can be two generations a year in most areas. Drawing by Andrew Schaible

Hornworms are the larvae stage of the Tobacco, Hawk, or Tomato Sphinx Moth. They have a large horn on the
posterior end of the body, which is how they get their name. The tobacco hornworm has seven diagonal stripes
on each side of the body, while the tomato hornworm has eight chevron-shaped stripes.

Damage
Hornworms are daytime feeders, and will feed on just about everything--blossoms, leaves, and fruit. When a
hornworm population is high, they will greatly defoliate plants and scar the fruit. Hornworms produce large, deep
cavities in the fruit. Usually they are not a problem in the warmer interior valleys unless their natural enemies are
disrupted, and then they can do serious damage. Hornworms can also occur in garden situations.

1.Antenna- none 6.Thorax- Potato Tuberworm
2.Eyes- 7.Petiole- none
3.Head- head capsule 8.Abdomen- abdominal segments 38
4.Legs- has thoracic & prolegs 9.Color-
5.Wings- none 10.Other-

Life Cycle 4
Female moths will lay eggs on tubers, foliage, or on the soil on a year-round
basis if it isn’t too cold. They will even find crevasses in the soil to reach Drawing by Andrew Schaible
tubers to lay their eggs. The larvae hatch and enter the tubers, excavating
tunnels. They will also go after foliage, even on tomatoes.

The Potato Tuberworm (Phthorimaea operculella, family name Gelechiidae) is not considered a problem in the
Northern California potato-producing areas, but it is under watch. In other areas, especially the Northwest, it can
be a serious pest. The adult is a moth with a wingspan of 1/2 inch. At rest the moth has a slender appearance. It
is gray colored with markings that are darker gray-brown or black. The tiny eggs are oval shaped, and range from
white to yellowish. Larvae are caterpillars that vary in color from dirty white to gray, pink, or green when feeding
on stems or leaves. They have a brown head and are just under 1/2 inch in length.

DAMAGE
High numbers of Tuberworms on very young plants may result in stand reduction or stunted plants. The damage
results from larvae tunneling in the tubers, which they enter at the eyes. Small deposits of frass can be seen with
webbing around an eye where larvae have begun to tunnel. The tunnel appears dirty as it is filled with excrement.

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