Beginner

Scientific Name
Trichoplusia ni

Identification

• Smooth and pale green
• Thin white line along each side
• Two faint lines down the middle of the back
• Moves like an “inchworm”
• Chews large ragged holes in the leaves

Often Confused With
N/A

Period of Activity
Cabbage looper do not usually appear until mid-July.  However, they have been found earlier in the southwestern municipalities of Chatham-Kent and Essex.

Scouting Notes
To monitor, count cabbage looper larvae on 30 randomly selected plants throughout the field by scanning leaves for damage.  Fresh feeding damage and frass are good signs that large larvae are present.  Look closely to distinguish whether the damage is due to loopers, cutworm, or hornworm.  

Threshold
Cabbage looper are unlikely to cause economic damage, but 15 larvae/ 30 plants has been suggested as a threshold.

Advanced

Scientific Name:
Trichoplusia ni

Identification
Adult cabbage looper are mottled greyish-brown moths with a distinctive silvery figure eight pattern on their forewings and a slight tuft of hair behind the head.  Their wingspan is about 3.8 cm (1 ½ in.).  Eggs are small, rounded and greenish-white, usually in small groups on the underside margins of leaves.  Cabbage looper larvae are light green with a white stripe along each side of the body and two faint lines down the middle of the back.  Since their legs are confined to the front and rear of the body, they move in a very distinctive “looping” manner.  Cabbage looper larvae reach about 4 cm (1 ½ in.) in length.  The pupa is initially light green in a loose cocoon, darkening in color as it matures.

Loopers feed on tomato foliage, chewing irregular holes in leaves, giving them a ragged appearance.  Loopers rarely feed on fruit, but may enter fruit previously damaged by other pests.  This pest may attach its cocoon to the tomato fruit.  Tomato plants can tolerate up to 25% defoliation by the cabbage looper without significant yield loss.

Often Confused With
N/A

Biology
Adult female cabbage looper lay several hundred small, rounded, white eggs, usually in small groups on the underside of leaves.  Larvae hatch after 3- 4 days and begin feeding on the foliage.  The larvae develop through 5 instars in 2- 3 weeks, then pupate in webbed cocoons on the leaves or fruit.

Period of Activity
Cabbage looper do not usually appear until mid-July.  However, they have been found earlier in the southwestern municipalities of Chatham-Kent and Essex.

Scouting Notes
To monitor, count cabbage looper larvae on 30 randomly selected plants throughout the field by scanning leaves for damage.  Fresh feeding damage and frass are good signs that large larvae are present.  Look closely to distinguish whether the damage is due to loopers, cutworm, or hornworm. 

Threshold
Cabbage looper are unlikely to cause economic damage, but 15 larvae/ 30 plants has been suggested as a threshold.

Management Notes

• Insecticide treatment is rarely warranted.
• Insecticides are less effective against large larvae.