Hi Tim,
This looks like two issues at play. The tree definitely had insects! Whether or not they were part of the tree's demise is not certain. Some insects attack stressed, or already dead trees. The bark at the base of one of the trees looks like it might have been a  young ash or elm? It's hard to tell without seeing branches/twigs. Both are known to die early due to invasive species (emerald ash borer) or invasive fungal diseases (Dutch elm disease).

The infestation of insects attracted the attention of a woodpecker! Likely a pileated? Have you seen those around? The actively cause the type of chips or chunks of wood that surround the tree on the ground. This is typical behavior of a woodpecker. 

Healthy trees can generally ward off native insect infestations. Signs of a tree struggling generally manifest themselves in the canopy, or upper branches, first. So, this spring you can monitor the health of the remaining trees by keeping watch over the leaves in the upper branches. Are leaves turning color and dying in the middle of summer? Are entire branches dead? Look for fresh sawdust at the base of the trees (if no rain has occurred). All of these are signs the tree is not healthy, and you may want to seek help at that point. 

For now, it looks like this was isolated to a few trees, likely of the same species. I wouldn't worry too much about it. 

If you have any questions, please do feel free to reach out. 

Thank you,
-Julie