Hannah, Yellowing between the veins of older leaves generally indicates a lack of a transportable nutrient, such as Magnesium. What is the analysis of the Plantacote? It could be that it is too slow releasing for the needs of the A. x calidora. These plants are very vigorous and that means they need enough nutrients to sustain that growth. Otherwise, they will decline and die down or out. I give my host of Alocasia hybrids a soluble fert solution every week and I use a higher nitrogen mix as well, occasionally supplementing with extra iron and manganese. Even under these conditions, some of mine get a little pale from time to time, especially in the summertime growing months. Many, if not most, of these Alocasia like well draining soil mix as well, so if your soil is heavy and wet, that might be part of the problem. Healthy roots are a must for proper nutrient uptake. Hope this helps, LariAnn Garner Aroidia Research Here is a link that might be useful: Alocasia x calidora

Could you possibly get pictures of these brown areas and holes and the green spider-like bugs that are on them? I'm not quite sure what you mean by "dewy". Also, the scientific name (latin name) of the plant would help me in my search for a solution.

My EEs do well all summer, but had a new experience happen with the black taro that is in a pot right beside it. The BT was failing, no matter what I did it would not thrive, tho the ones in the garden pond and in the ground 15 feet away were doing well. I finally decided to just pull the poor dead plants from the pot and let the rest of the plants take over. To my surprise the roots were totally gone! I have wave petunias, allysum and another foliage plant in that planter and they are all fine, only the taro was struggling. Someone had mentioned earwigs eating roots, think it was Paul James on one of his shows. I have seen a lot of earwigs in the crevices of that plant, do you think they are the culprit? Why only that plant?

Sun scorch maybe? Looks like the damaged leaves are all in the front and see to line up with the change in color on your patio. I know this time of year I have to readjust some plants as some parts of my yard that get mostly sun in June are all shade now and vice-versa. Or if they are the oldest leaves on the plant it might just be their time.