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The obliquebanded leafroller
is a native species that occurs throughout southern Canada and the United States. It infests apples, pears, cherries, plums, peaches, roses, raspberries, gooseberries, currants, strawberries and many weeds, and it is a major pest of blueberries. Facts:
- The eggs are laid in patches that measure about .275 in. by .551 in. (7 mm by 14 mm) and contain up to 200 eggs. The mass is covered with a cement that, when dry, gives the mass a dull, greenish yellow color. Just before hatching, the black head capsule can be seen.
- In the larvae, the head capsule is .066 in. to .074 in. (1.7 mm to 1.9 mm) wide and light to dark brown or black, though color can vary considerably. All instars have dark brown or black heads, thoracic shields and legs and yellowish green bodies. The coloration of the prothoracic shield varies considerably. Summer-generation larvae have little brown pigmentation; spring larvae and overwintering larvae have more extensive and darker coloration. With bodies that range from .78 in. to 1.18 in. (20 mm to 30 mm) long, the obliquebanded leafroller larvae are the largest leafroller larvae found in commercial orchards.
- The pupae at first are light greenish brown, but they change to a deep reddish brown later. Pupae are about .44 in. to .53 in. (11.4 mm to 13.5 mm) long.
- The adults are banded with various shades of tan to chocolate-brown scales. The female is much larger and usually more strongly colored in the forewings; in the hindwings, the distal half is yellowish. Wing span is .94 in. to 1.18 in. (24 mm to 30 mm) for females and .67 in. to .91 in. (17 mm to 23 mm) for males.
- This insect overwinters as a second- or third-instar larva within a hibernaculum. The hibernacula are found under old bud scales or fragments of the bark, within cracks or roughened areas, and in twig crotches. The hibernacula exteriors are covered with fecal pellets that weather to a dirty gray, similar to the color of surrounding plant surfaces.
- Activity resumes in the spring when the larvae leave the hibernacula and bore into the opening buds. Later, when the leaves become larger, they fold leaves into tubular chambers where they remain concealed except when feeding.
- When disturbed, they will desert this shelter, spinning down on a strand of silk.
- Pupation occurs within the feeding site and lasts 10 days to 12 days.
- A female is capable of laying up to 900 eggs in her seven-to-eight-day oviposition period.
- Newly hatched larvae quickly desert the leaves on which they hatched and crawl to leaves nearby or lower themselves by silk strands to other leaves. Winds can transport larvae on these threads for some distance. The larvae select an initial site for feeding on the undersurface of a leaf along the midrib or other large vein.
- First-generation larvae feed on water sprouts and fruit.
- A shortage of water sprouts may limit their numbers because first-instar larvae need actively growing leaves or fruit tissue.
- Pupation takes place in their final feeding sites.
- The incubation period and the activity of the second-generation larvae are the same as those of the first generation.
- Most of the larvae overwinter on the host plant.
- Some first-instar larvae will be carried on their silken threads to other hosts. Second-generation larvae feed until they reach the third instar.
- At this time, they seek out suitable winter quarters on the tree and spin a hibernaculum.
- Premature fruits drop before they are ripe.
- Developing fruit may exhibit deep, corky scars and indentations at harvest.
- Leaf injury is characterized by the larvae rolling leaves and feeding on surrounding foliage.
- Check on upper leaf surfaces.
- Use pheromone traps to monitor for adults.
- Several parasites attack obliquebanded leafroller larvae but do not adequately control the pest. Insecticides, effective against large larvae, must be applied at petal fall. If necessary, another spray should be applied in the summer, when most of the summer brood eggs have hatched.
- An alternative strategy is to control overwintering larvae at petal fall as previously described, and apply sprays during June to kill the first summer brood adults and newly hatching larvae. Conventional organophosphate insecticides can be used in this program. The flight of adults can be monitored with pheromone traps. The first spray should be applied about 7 days after the first male moth is captured and subsequent sprays should be applied at 14-day intervals as long as the flight continues.
- Check with your local Cooperative Extension Service office for control measures for your area.