Jackfruit Shoot Borer
Diaphania caesalis
The major insect pest of jackfruit, a moth whose caterpillars bore into the tender shoots, flower spikes, and fruit. Hidden inside the plant, the larvae rot the growing tips and flowers and tunnel into fruit, deforming or destroying the crop.
🔎 How to spot it
The damage is the giveaway, since the caterpillars feed inside: look for bored shoots and flower spikes with holes plugged by frass (sawdust-like droppings) and webbing, wilted or dead shoot tips, and rotting male flower spikes. The larvae are caterpillars that tunnel within tender growth and fruit, and the adult is a small moth active at night.
🥀 Damage it causes
Larvae bore into tender shoots and into the male and female flower spikes, so attacked spikes fail to open, rot, and shed, and infested young fruit is deformed or drops. In mature fruit the caterpillars tunnel into the edible flesh, fouling it with frass, and infestation rises sharply in wet weather.
🛡️ Prevent it
Prune and train trees to keep the canopy open and well ventilated, which lowers humidity and the borer along with it, and remove and destroy infested shoots, dropped flower spikes, and damaged fruit to break the life cycle. Bagging developing fruit protects it from egg-laying, and clean orchard sanitation reduces carryover.
🧯 If it is already here
Because the larvae are protected inside the plant, control depends on removing and destroying infested shoots and fruit and on timing any sprays to the egg and young-larva stage before they bore in, guided by monitoring of new flushes and flowering. An integrated approach of sanitation, pruning, fruit bagging, and conserving natural enemies manages it better than insecticides alone.
💡 Good to know
Frass-plugged holes and webbing on shoots and flower spikes are the field signs to scout for. Damage tracks rainfall closely, so vigilance and sanitation through the wet, flowering, and fruiting season pay off most.
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.