Banana moth—Opogona sacchari
The larval stage of banana moth (family Tineidae) is a chewing pest that tunnels in various hosts. In California it feeds on palms, especially queen palm.
Identification
Because the larvae feed hidden within plant tissue, symptoms of its presence as described below under Damage are commonly the first clue that banana moth is present.
Adult banana moths have forewings that are dark grayish or yellowish brown, each with one black spot. The hind wings are silvery with a dense fringe of hairlike setae. The moth is about 1/2 inch long with a wingspan of about 4/5 inch.
Eggs are oval and translucent to whitish or dark to pale yellow and about 1/30 inch (0.8 mm) long. They are commonly laid in a group in crevices of the plant near or on wounds.
Larvae are translucent, pale green, or whitish. They have 3 pairs of small legs and grow up to 1-1/8 inches long. They have blackish to brown spots on top and along the sides and a brown head. Where larvae have fed there are masses of their reddish brown frass (excrement).
Pupae are oblong and initially pale but become dark brown as they age. They are about 1/2 inch long. Before the adults emerge, pupae can sometimes be observed partially protruding from the entrance of tunnels where they fed during the larval stage.
Life cycle
Banana moth develops through four life stages: egg, larva, pupa, and adult. The larvae are primarily detritus feeders and scavengers that feed on decaying organic matter of virtually any plant. For a complete list of plants on which it is reported to sometimes feed see HOSTS - a Database of the World's Lepidopteran Hostplants and Opogona sacchari (banana moth).
The adult females are attracted to stressed plants and where there is decaying or dead plant tissue for egg laying. Egg laying sites include fresh wounds such as cut petioles or leaf bases of recently pruned palms. Protected places where eggs are laid include existing crevices or wounds, behind leaf bases or bracts of inflorescences, and among the fibers of leaf base margins. Females will also oviposit at the plant base where larvae will bore in and chew inside roots. Each female lays about 50 to 200 eggs during her lifetime.
If feeding around leaf bases, the larvae will eventually bore into the apical meristem (the growing point from which new leaves arise), damaging or destroying this central growing point. The damage also allows the apical meristem and newest leaves to become infected with secondary pathogens such as pink rot.
Damage
Banana moth prefers to attack nursery stock but in Southern California it occasionally infests palms in the landscape. The first obvious symptom of an infestation is generally the growth of damaged or dead leaves caused by the caterpillars feeding around or in the apical meristem. If the palm recovers from such an attack, the first several leaves produced will be atypically small. With some infestations there may be no foliar symptoms at all.
The larvae can attack nearly all parts of a palm including frond petioles and stems and roots. If the base of stems where new roots emerge are fed upon, collapse (tipping over) of the trunk can be the first indication this pest is present.
Banana moth prefers to infest plants that are stressed or wounded. In landscapes and nurseries, it can potentially infest a wide variety of palms and certain other plants such as Dracaena species. In Southern California it has infested bamboo palms (Chamaedorea species), Chinese windmill palm (Trachycarpus fortunei), majesty palm (Ravenea rivularis), and queen palm (Syagrus romanzoffiana). Infestations in palm are generally associated with pink rot disease that in combination with the tunneling larvae can kill various plant parts and eventually the entire palm.
Solutions
When purchasing palms, carefully inspect them for pests. For banana moth examine around the base of the plant where new roots are produced and around the apical meristem. If tunnel entrances, dark granular frass, or oozing are observed, reject the plant. Consider purchasing from a different grower selling uninfested plants.
Prevention may be the only effective management strategy. Minimize palm stress and maximize palm health and vigor. Providing adequate irrigation during the drought season and periodic fertilization with a product specifically labeled for palms are especially important.
Inspect valued palms frequently to ensure they are receiving proper cultural care and a good growing environment. Avoid excessive pruning. Where banana moth is known to occur, consider treating freshly cut palm surfaces with a systemic insecticide such as acephate or imidacloprid if the product is labeled for that use.
Adapted from The Biology and Management of Landscape Palms, International Society of Arboriculture and University of California. See this publication for more information and photographs of banana moth and other palm pests. |
