I would think it is the young caterpillars of teak defoliator that are scraping the leaf surface, based on the damage and the frass in pic 3.
Can you open the leaf fold shown in pic 2 and check if there is a caterpillar inside?
I would think it is the young caterpillars of teak defoliator that are scraping the leaf surface, based on the damage and the frass in pic 3.
Can you open the leaf fold shown in pic 2 and check if there is a caterpillar inside?