Jason asks: A few leaves on some of the banana trees on my property have sections that are rolled up. Is this a disease? If so, what should I do about it?
Jason asks: A few leaves on some of the banana trees on my property have sections that are rolled up. Is this a disease? If so, what should I do about it?
Tropical Gardener answer: Your description of the leaves sounds like the work of a banana skipper larva. The larva emerges from one of the eggs that the butterfly (Erionota thrax) lays on the underside of banana leaves. When the eggs hatch, a white caterpillar emerges and begins eating and growing. As the caterpillar grows, it makes a roll in a section of a leaf to hide while it continues to eat and finally pupate into the adult moth.
The banana skipper butterfly first appeared on Oahu in the early 1970s. Fearful of the potential threat this pest posed to banana production, the Hawaii Department of Agriculture imported parasites that would attack the skipper’s eggs and larvae. These parasitic predators remain and have managed to keep the banana skipper population under control.
Though human intervention is not usually necessary, close observation can help prevent the damage the skipper causes. The adult wingspan is less than 3 inches. The wings are chocolate brown with two lighter spots on the top wings and some varieties have red eyes. If you see her in your garden, start looking for eggs on the underside of banana, heleconia, canna, bird of paradise and palm leaves.
The eggs are small and white but turn orange just before hatching. If you find the eggs before they hatch, destroy them. If they have hatched, look for caterpillars. They are fairly small and somewhat transparent when young but can grow large and a ghostly white with a black head after feeding for a few days. If you see their black frass (poop) on the leaves continue looking. At this stage the caterpillars are susceptible to human intervention either by killing them in a jar of alcohol or by spraying a Bacillus thuringiensis product on the leaves. Caterpillars that eat but die in a few days.
In many cases, you may see the rolled leaves but won’t find the caterpillar. This means it has already pupated or the predator is doing its job.
Some questions that appear here were originally directed to Kona’s Certified Master Gardeners.
You may contact them with questions at konamg@ctahr.hawaii.edu.
Diana Duff is a plant adviser, educator and consultant living on an organic farm in Captain Cook.
Farmer Direct Markets
Wednesday: “Hooulu Farmers Market,” 9 a.m. to 2 p.m. at Sheraton Kona Resort and Spa at Keauhou Bay
Wednesday: “Sunset Farmers Market,” 2 p.m. to sunset at the north makai corner of the Kmart parking lot
Saturday: “Keauhou Farmers Market,” 8 a.m. to noon at Keauhou Shopping Center
“Kamuela Farmer’s Market,” 7 a.m. to noon at Pukalani Stables
Sunday: “South Kona Green Market,” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook
Tuesday–Saturday: “U-Pick greens and produce,” 10 a.m. to 4 p.m. Tropical Edibles Nursery in Captain Cook
Plant Advice Lines
Anytime: konamg@ctahr.hawaii.edu
Tuesdays and Thursdays: 9 a.m. to noon at UH-CES in Kainaliu, 322-4892
Mondays, Tuesdays and Fridays: 9 a.m. to noon at UH-CES at Komohana in Hilo, 981-5199 or himga@hawaii.edu.