leafroller, Ancylis comptana fragariae, was inadvertently introduced
into North America from Europe in the 1800s and was recorded as a pest
of strawberries in Illinois over 125 years ago. It is now distributed
throughout the United States.
Strawberry leafrollers overwinter as larvae or pupae in folded leaves
or leaf litter. Adult moths emerge in April and May and deposit translucent
eggs, usually on the lower surface of strawberry leaves. Moths are reddish
brown, with distinctive yellow markings on the forewings; their wingspan
is approximately 1/2 inch. As larvae feed and grow, they change from pale
green to grayish brown in color. Mature larvae reach a length of 1/2 inch.
Leafroller, adult and larva. Adults wingspan and larval length are
about 1/2 inch.
As larvae feed, they secrete silken threads to fold and tie strawberry
leaflets together. Within these folded leaves, larvae feed on only the
epidermis of each leaf, but entire leaflets usually turn brown.
leafroller completes 2 or 3 generations of development each year, and
moths of the summer generations are often present from July through September.
Infestations may develop in spring and early summer, but they may also
build up after harvest.
Two parasites, Macrocentrus ancilovorous and Cremastes cookii,
often kill a high percentage of strawberry leafroller larvae, especially
during summer generations. Low levels of leafroller infestation (ill-defined,
but perhaps 10 to 20 percent of strawberry leaflets, especially after
harvest) do not warrant control because they do not cause reductions in
plant vigor or yield during the current or subsequent season. Where control
is necessary, consult the most recent edition of the Illinois Commercial
Small Fruit and Grape Spray Guide for a listing of registered insecticides.
leafroller and the blueberry leafroller also feed on strawberry foliage,
but although both are common on several fruit crops and weeds, neither
commonly causes significant damage to strawberries. The nature of the
damage that they cause is similar to that of the strawberry leafroller,
and the same insecticides may be used for their control in the rare instances
where treatment is warranted.
leafrollers occur in many fields, these pests do not damage berries directly
and often do not reach high densities. Consequently, controlling them
is often unnecessary. Insecticide applications for the control of foliage-feeding
pests can and should be based on scouting results, not preventive spray