General
The banana moth or banana borer (Opogona sacchari, also known as Opogona subcervinella) belongs to the family of Tineidae. Outside of tropical zones, the banana moth (Opogona sacchari) can only establish in greenhouses. The insect has been repeatedly encountered in different European countries, but was eradicated in some. The species is polyphagous and feeds on plants of 22 families. It is an important pest in banana and can also attack tropical crops such as pineapple, bamboo, maize, potato and sugarcane. The caterpillars are polyphagous and prodigious feeders, attacking large numbers of ornamental plants of tropical or sub-tropical origin that are now cultivated in European greenhouses. Dracaena, yucca, strelitzia and cacti are hosts, and occasionally dieffenbachia, euphorbia, bromeliads and ficus function as host as well.
Life cycle and appearance of Banana moth
Adults of the banana moth (Opogona sacchari) are almost uniformly clear, yellowish-brown. The moth is about 1 cm long with a wingspan of 18 to 26 mm. The forewings are brown suffused with a golden glow and with two small black dots, and may display dark brown bands. The hindwings are paler and clearer. The banana moth (Opogona sacchari) is a typical nocturnal moth, but unlike other nocturnal moths it holds its antennae straight out in front when at rest.
The eggs are light yellow at oviposition and turn a dark yellow colour ca. two days later. Shortly before eclosion they turn a yellowish brown. There are six or seven larval stages. The larvae are at most about 3.5 cm long, are highly mobile, photophobic and gluttonous feeders. They withdraw very rapidly into affected plant material. They are dirty white to grey-brown and partially transparent, such that the internal organs can be seen. They have a bright red-brown head with clearly visible brownish plates on the thorax and abdomen. The larvae normally live in the crown of banana, in the stems of ornamental plants, or in leaves or stalks.
The pupae are brown and usually less than 1 cm long. The cocoon is spun at one end of a borehole and is usually 1.5 cm long. Before the moth emerges, the pupa works itself partially out of the plant tissue by means of two small hooks. Beside these hooks, the pupa also has conspicuous spines on each segment. The most striking feature of this insect is that the empty pupal case is left hanging out of the passage in the plant tissue. Occasionally pupation may take place in pots.
Damage symptoms
Caterpillars make passages and holes in both woody and succulent crops. In ornamental crops the larvae are found mainly in the stalks, and sometimes in leaves and cotyledons. The presence of yellow white dust left in the openings of bore passages is characteristic of an attack of the banana borer. Seedlings can be very badly affected. The attack is not usually recognized in its earliest stages. The caterpillars normally begin to eat into the phloem and woody tissues and leave the bark standing. Because the flow of sap is interrupted, the plant begins to wilt. In yucca, for example, the bark is flaccid to the touch and can be dented with the finger in the affected area. In cacti, yuccas and dracaena, for example, the stems may be completely hollowed out. Plants whose roots or stem base have been attacked, first lose a few leaves and then collapse (e.g. sanseveria and palms).
In addition to the direct damage they inflict, the indirect damage should also not be underestimated. Damaged areas can be invaded by moulds and bacteria and begin to rot as a result. This can exacerbate the damage and produce unpleasant odours.