I have (sorry, had) 2 Japanese Waterfall Maples. One is thriving beautifully, the other died. They were both planted at the same time, are both in the same area, get the same amount of water, sun, etc. When I dug up the root ball of the dead tree, I found little yellow pods, hundreds of them. They seem dry and empty. Does anyone know what this is? Is it an insect that has killed my tree? And if so, how do I protect the other tree?

Thanks