"The bottom fronds of our triangle palm started to die, and
then suddenly the whole palm fell over," a friend complained.
A significant pest
of Pritchardia palms is the banana moth, Opogona sacchari. The triangle
palm is also attacked by this moth. It seems that the female moth targets
wounded or stressed palm tissue to lay her eggs. Stresses can include drought,
flooding, mechanical wounding, poor nutrition, and herbicide injury. The larvae
generally feed on decaying and dead plant tissue but will feed on living
tissue, too, causing extensive damage. In affected palms, larval tunneling,
along with the characteristic frass (insect droppings), can often be seen.
Fully developed caterpillars measure just over an inch. The adults have greyish
brown wings are 3/8 to 5/8 inches long.
The main treatment
is prevention: keep palms growing well; give them adequate fertilizer, and
supplemental water during a drought. Gardeners also need to be careful with the
weed wacker! Female moths are looking for wounds to lay their eggs. Bt
(Bacillus thuringiensis), an organic insecticide, can be applied to these
wounds, as well as those caused during pruning.
For more information about this pest see the CTAHR Cooperative Extension Service publication, “Banana Moth – A Potentially Fatal Pest of Pritchardia and Other Palms”, by Scot Nelson and Mark Wright. CTAHR stands for the College of Tropical Agriculture and Human Resources at the University of Hawaii.
