Leaf Rollers

Pests of Field Crops in Southern Africa

LEAF ROLLERS

(Lepidoptera: Pyralidae)

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Text Box: A fairly commonly found leaf-rolling caterpillar found in soyabeans is the larval stage of the moth, Sylepta derogata. The larvae are almost translucent green, and have a dark head and area behind the head. They reach 15 to 20 mm in length, are slightly hairy and are tapered at both ends. They are very active, wriggling or darting backwards when disturbed within the rolled and tied-up leaves where they feed and take shelter. The moths are tan brown, with wavy, darker brown transverse lines across the wings. TOP

Text Box: Besides soyabeans, this species is fairly polyphagous and has been recorded on cotton and other Malvaceae (particularly okra). On one occasion, an interesting case of leaf roller on maize has also been recorded, and although no confirmed identification was made, the larvae and adults appeared to be the same species (damage was confined to the leaf tips, which were rolled over, and filled with frass). TOP

Text Box: Although leaf rollers never reach the same density that semi-loopers can reach, they are quite commonly found in soyabeans. The young leaves at the top of the plant are usually rolled up and tied together, and the leaf itself may have a dimpled or puckered appearance, as if the blade has been unable to expand normally. The caterpillars consume the rolled up leaves, and the area inhabited is usually filled with frass and some webbing. Significant damage by his pest has never been seen. TOP

Text Box: The small, pale oval eggs are laid singly on the leaves. The newly hatched larvae tend to congregate in rolled up leaves after a short time of wandering, but later disperse and form their own leaf rolls. TOP

Text Box: It has rarely been considered necessary to apply control measures for this pest, and if left unsprayed, it undoubtedly comes under natural control. If used, most semi-looper sprays would give control. TOP

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Typical leaf roller symptom in Soya beans.

Leaf roller frass and webbing in opened leaf.

Soya bean crop.