UF/IFAS Vegetable Arthropod Pest Photographs CD-ROM III

Melonworm, Diaphania hyalinata
(Lepidoptera: Pyralidae)

The melonworm is found throughout Central and South America and the Caribbean. The United States is generally the northern limit of its range. The melonworm disperses northward annually and occurs during the summer months principally in the southeastern states. The melonworm can complete its life cycle in about 30 days. Three generations are usually completed before cold weather kills host plants. The eggs are oval in shape and are white or greenish but usually become yellow. The larva is colorless when first hatched but assumes a green color with a white line along each side of its back. The larva usually constructs a loose silken structure under leaves, which serves as a shelter during the daylight hours. The larva will spin a cocoon on the host plant, often folding part of the leaf over itself for added shelter. The pupa is light to dark brown in color and is fairly pointed at each end. The adult has wings that are pearly white centrally, bordered with a dark brown band. The adult melonworm remains in the crop during daylight hours but is mainly active at night.

The melonworm is restricted to feeding on cucurbits. Hosts include pumpkin, cucumber, squash, gherkin, and cantaloupe, with summer and winter squash its main host. The melonworm feeds primarily on foliage and may also feed on the rinds of fruit. In some circumstances, the melonworm may burrow in fruit. Melonworm is sometimes referred to as a rindworm. Young plants should be sampled for melonworm by checking plants for early stages of leaf damage and the presence of larvae. A variety of insecticides are available to control melonworm but should be used selectively because of pollinators that are required for the crop. Row covers may also be used in small plots to exclude melonworm adults. Trap crops (early plantings) may also be used and destruction of plant residues is recommended.

Images

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Melonworm, Diaphania hyalinata, mature larva.
(Photographer: J. Capinera, University of Florida)
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Melonworm, Diaphania hyalinata, adult.
(Photographer: J. Capinera, University of Florida)
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Defoliation of squash by melonworm, Diaphania hyalinata,
larvae.
(Photographer: J. Capinera, University of Florida)
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Melonworm, Diaphania hyalinata, newly emerged larva
and eggs.
(Photographer: R. Duncan, University of Florida)
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Melonworm, Diaphania hyalinata, late instar larva feeding
on leaf.
(Photographer: P. Choate, University of Florida)
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