Leaffolders and Webworms
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Contents |
Importance
A complex of leaffolding and web-making larvae feed on sycamore leaves. Ancylis platanana, occurring only on Platanus throughout the Eastern United States, is emphasized here. Heavy defoliation of small groups of trees may occur. Repeated defoliation may reduce growth and incite crown dieback.
Identifying the Insect
Larvae of A. platanana are slender and pale yellow with smooth bodies; mature larvae are 9 to 11 mm long. The forewings of adults are reddish with white markings. Eggs are small, oval, and almost colorless.
Identifying the Injury (fig. 4b, c)
Small, silken shelters are found on the undersurface of partially skeletonized leaves. A leaf gradually becomes folded and is further webbed and skeletonized, often leaving only a brown network of the larger veins. Injury by other webworms is similar but with more extensive webbing.
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| Figure 4b. - Advanced feeding and extensive webbing. |
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| Figure 4c. - Heavy defoliation |
Biology
Adults of A. platanana emerge from March to May and deposit eggs singly on the undersides of leaves. Eggs hatch in 3 to 5 days, and the young larvae feed along the leaf midrib. Older larvae pull the leaf over into a fold and feed for about 6 weeks until they pupate beneath the webbing in the folded leaf. The pupal stage lasts 9 to 11 days before the adults emerge. There are three to four generations per year. Overwintering occurs as prepupae in fallen leaves.
Control
Natural enemies help control populations. Some control is possible by disking to bury fallen leaves and pupae.
References
Leininger, T.D; Solomon, J.D.; Wilson, A. Dan; Schiff, N.M. 1999. A Guide to Major Insects, Diseases, Air Pollution Injury, and Chemical Injury of Sycamore. Gen. Tech. Rep. SRS-28. Asheville, NC: USDA Forest Service, Southern Research Station. 44 p.
