Bark-Eating Caterpillar
Indarbela tetraonis and Indarbela quadrinotata
A wood-boring caterpillar, often called the bark borer, that attacks the trunk and main branches of sapodilla and many other fruit and shade trees. The larva hides in a tunnel by day and creeps out at night to graze the bark beneath a sheltering web of silk and chewed-wood frass, slowly sapping the tree of vigor.
🔎 How to spot it
The larva is a stout, reddish-brown caterpillar that can reach about an inch and a half (37 to 43 mm) long, living inside a bore hole in the bark or wood. The adult is a stout grayish moth. The most recognizable sign is on the bark itself: irregular, zigzag ribbons and galleries of silk webbing mixed with brown frass and chewed bark plastered over the trunk and branch forks, with a tunnel entry hidden underneath.
🥀 Damage it causes
The caterpillar bores a tunnel into the trunk or a main branch and comes out at night to feed on the surrounding bark under its protective web. This bark feeding and tunneling disrupt the flow of sap, weaken the framework branches, reduce vigor and yield, and on young or heavily attacked trees can cause dieback. The silken frass-covered patches are unsightly and mark active infestations.
🛡️ Prevent it
Keep trees healthy and the orchard clean, and inspect trunks and branch crotches for the tell-tale silk-and-frass ribbons. Remove and destroy badly infested, declining branches, and reduce nearby alternate host trees such as guava and other fruit trees that harbor the pest. Catching young infestations early, before larvae tunnel deep, makes control far easier.
🧯 If it is already here
Scrape away the webbing and frass to expose the bore hole, then kill the larva inside by probing the tunnel with a stiff wire, or by plugging the hole with a swab soaked in a registered insecticide (or kerosene) and sealing it; trunk swabbing with an insecticide has given good control where the pest is a problem. Because the larva is shielded inside the wood, cover sprays alone are ineffective and treatment must reach into the hole.
💡 Good to know
There is generally one generation a year, the long-lived larva taking the better part of a year to mature before the moths emerge in the rainy season. The caterpillar is highly polyphagous, attacking sapodilla, guava, mango, and many other fruit and forest trees, mainly in tropical Asia, where it has no U.S. cooperative-extension page; the facts here are drawn from the strongest available horticultural and research sources.
🌱 Plants it attacks
14 plants in the library can be attacked by this pest
For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.