Hi Julie,

It's been a hard couple of years for trees. Drought has meant many are struggling, and this insect preys on stressed trees.

Here's information on two-lined chestnut borer:

https://extension.umn.edu/tree-and-shrub-insects/metallic-wood-boring-beetles

I'd encourage you or your neighbor to consult a certified arborist who may be able to pin down what's going on with these trees. In the meantime, they should be watered. Lawn irrigation systems don't provide enough water for big trees. An oscillating sprinkler that waters the entire area under the tree canopy for several hours on a still day is the best way to help these oaks.

You can find a certified arborist at the website below. I found several arborists from Northfield, which should be near you.

https://www.treesaregood.org/findanarborist

Good luck.