Tree Fruit Insect Pest - Green Fruitworm

The speckled green fruitworm, Orthosia hibisci, is the most common of several green fruitworm pests occurring in commercial orchards.
Tree Fruit Insect Pest - Green Fruitworm - Articles
Tree Fruit Insect Pest - Green Fruitworm

Several narrow white stripes run longitudinally along the top of the body, while a slightly wider, more distinct white line runs along each side. Photo by Greg Krawczyk.

The larvae feed on a variety of deciduous shade, forest, and fruit trees including apple, pear, and cherry. These pests have only one generation annually.

Description and life cycle

Adults are night-fliers whose flight period closely parallels apple bud development. Flight begins at about green tip, peaks at tight cluster, and ends by the pink stage. Adults are about 2∕3 inch in length. Their forewings are grayish pink, each marked near the middle by two purplish gray spots outlined by a narrow, pale border. The hind wings, not visible when the moth is at rest, are slightly lighter in color than the forewings. Freshly laid eggs are white with a grayish tinge and have numerous ridges radiating from the center. Shortly before hatching the egg takes on a mottled appearance. Newly hatched larvae are ¼ inch long and have a grayish green body with a brown head and thoracic shield. Mature larvae are 1 3∕16 to 1 5∕8 inches long and have a light green body and head. Several narrow white stripes run longitudinally along the top of the body, while a slightly wider, more distinct white line runs along each side. The green areas between the stripes are covered with numerous white speckles. Pupae are dark brown and about 5∕8 inch long.

Injury

Females begin egg laying on twigs and developing leaves when apples are in the ½-inch green stage. A female is capable of laying several hundred eggs but normally deposits only one or two at any given site. Young larvae feed on new leaves and flower buds and can often be found inside a rolled leaf or bud cluster. Older larvae damage flower clusters during bloom and continue to feed on developing fruit and leaves for 2 to 3 weeks after petal fall. They then drop to the ground, burrow 2 to 4 inches beneath the soil surface, and pupate over the winter.

Most flower buds and blossoms damaged by larvae abort. Most fruit damaged just before and shortly after petal fall also drop prematurely. Some, however, remain at harvest and exhibit deep corky scars and indentations. This injury is indistinguishable at harvest from that caused by the overwintering larvae of the obliquebanded leafroller.

Monitoring and management

Orchards with a history of green fruitworm injury should benefit from effective insecticide applications at the petal fall.

Authors

Insect plant interactions Integrated pest management Biological control Tree fruit insect pests Insects rearing Laboratory and field bioassays Invasive insect pests Pesticide resistance

More by Grzegorz (Greg) Krawczyk, Ph.D.