Can you help me identify this plant?

HI, I planted a 6 foot dwarf honey crisp apple tree 10 years ago. It produced apples the first two years and now the past 8 years, early in the fall season it will start growing leaves and then the same thing happens to the leaves and the apples stop growing. We have an underground sprinkler that goes off daily in the summer and not sure if that is causing an increase in bacteria. But I'm not sure if this is bacteria or a bug infestation. In the past I have put fertilizer sticks around the bottom of the tree roots and added more mulch.

I read a short article from 2017 on this website which indicated that these beetles were somewhat rare in Michigan. This is the fourth year I have had them appear, and I would characterize them as invasive: in both the lawn and in gardens there are large numbers. For example, on one chive plant I counted at least 15. Other than my neighbor, I don't know anyone who has a problem with them. They appear at the end of the summer. They also have shown up on my garage floor. I am worried about their toxicity and effect on the skin. Is there anything I can do aside from spraying each beetle individually with insecticide, which seems to work. That is unfortunately completely unrealistic.