Cucumber moth

Diaphania indica (Saunders)

Lepidoptera: Pyralidae

The cucumber moth is reported from all continents in tropical and subtropical areas.

Host plants and damage

Cucumber moth is primarily a pest of Cucurbitacae. However, it has also been recorded from the leguminousae Glycine max.

Economically important hosts are Cucumis melo (sweet melon), Citrullus lanatus (watermelon), and Cucumis sativus (cucumber).

Larvae feed on leaves, fruits, and pods. Early symptoms of infestation are leaves folded and bound together by young larvae. Larvae are feeding between the leaf veins. Remaining leaves look like patches of network.

Morphology & biology

D. indica is often confused with Diaphania hyalinata. D. indica can be distinguished by the absence of an extension for the brown marking on the forewing. Specialists can separate all species in the genus Diaphania by examination of the genitalia under a microscope.

Eggs are laid in singly or in clusters on the undersides of leaves. Number of eggs laid varies for different hosts. They are oval in shape, 0.7-0.8 mm in length and whitish in color. Incubation time for eggs takes 2-3 days at temperature above 14 °C.

First instars are transparent but change to a green color as they grow. Fully grown larvae are 18-25 mm. The larval period lasts 3-4 weeks.

Pupation takes place in a folded leaf and lasts for 8-12 days. Pupae are 12-15 mm and turn from green to brown as they develop.

Adult moths have transparent white wings with a brown band around the edge. Wing span is 25-30 mm. The adults have a brown tip on the abdomen.

The total duration of a life-cycle is 20-40 days, depending on temperature and host plant.

Monitoring

In early stages of cucumber moth infestations look for folded leaves and inspect areas with a lacy appearance.

In later stages inspect fruits for damage and entry holes by larvae.

Pest management

Biological control

Apantales taragamae Viereck is reported as parasitoid but was unable to control cucumber moth successful in the field.

Chemical Control

Several synthetic insecticides and Bacillus thuringiensis have been reported to be effective against cucumber moth. Both, systemic as well as contact insecticides can be used for control of cucumber moths.