Last year this alocasia 'giant taro' was very healthy growing foot long leaves shooting up every couple of weeks. At some point the leaves started to decay and while it's still alive, the leaves are small (4 inches long max) and they develop yellow spots which eventually turn brown.
I wonder if it's a pest as the underside of the leaves have some little black dots on and occasionally I have seen little black bugs crawling around. The soil is kept damp but not waterlogged.
A new leaf that has developed the problem almost immediately