Spruce and other conifer cones - actually the seeds - are an integral part of a squirrel's diet. And they don't have great table manners :-)) The only way to get them to leave the cones alone is to get rid of the squirrels.

@gardengal48 (PNW Z8/9) I needed something to smile about today - Not being too facetious but — Henry, gardengal’s point is exactly right based on my personal experience with conifers and squirrels. But, doing that will be an endeavor worthy of Sisyphus! Easier to get rid of the trees. Sorry! 😊

The tree is supplying food to wildlife. Birds also feed heavily on Norway spruce cones (the seeds) when the timing is right -- I've seen it. As others say, the only way to stop it is remove the tree.

Is there any way to stop them from making the yard messy?

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short of moving.. the answer is NO

remove the trees.. or remove the aunt... thats about it....

there isnt much squirrel left if you use the shotgun.. and its probably not legal anyway... i mean really.. you do live in ohio... so maybe it is... but what more can this UM guy say.. lol

https://duckduckgo.com/?t=ftsa&q=squirrle+stew&ia=recipes

ken