Entomologist here, they aren't beetles, they are nymphs of some kind of true bug (suborder Heteroptera). They don't look quite right for stink bug or leaf-footed bug nymphs, but are likely related to those. See my other comment for more info.Yep, it's a beetle but I have no idea of what kind....tagging @aart
Might be a longhorn beetle? or another wood boring beetle.