Need help to identify problem

[jimmy0123]

My VFT has been growing poorly lately. Firstly the traps are more semi-open and quickly turns black. I fed a life mosquito larvae after a new trap open for a few days and after a week or so the center of the traps start showing a single black dot in the middle and few days later all turn black. Is the food i fed it too 'nutritious' for it or it showing sign of dormancy? I do notice in slow growth though. Any suggestion greatly appreciated.