Hi John,

There are many areas across Lower Michigan where green and white ash regeneration is abundant.  Most of these trees were too small to be colonized by EAB during the first big invasion wave.  While EAB will colonize, feed and develop on trees as small as 1 inch in diameter, those little trees won't produce many beetles.  And usually the trees are more like 3 inches in DBH before we see galleries. 

As you pointed out, the carrying capacity for EAB is now orders of magnitude lower than it was previously because most large overstory green ash and many overstory white ash have died.  Less ash phloem means fewer EAB larvae can develop in a given area. On the other hand, EAB is still around. You are correct in that there could be some level of resistance in the young trees on your property, assuming they regenerated from seed (i.e., not stump sprouts - those are as vulnerable as the parent tree). Also, there have been many releases of imported parasitoid wasps across most of Michigan.  These species, along with native parasitoids and woodpeckers (especially woodpeckers) will kill some amount of EAB larvae. We have not seen evidence yet that all of the natural enemies can prevent or even slow ash mortality but they help. 

In terms of your own trees, you might leave them for now.  In late fall, after leaf-drop, take a hard look at them, especially the green ash.  EAB consistently prefers green ash to white ash. If you see woodpecks on the upper portion of the leader, then EAB is present and there are probably larvae in that tree.  If not, I'd wait and see what happens.  Couple of points - any stressed tree will be more attractive than a healthy tree, green ash are more attractive than white ash and trees in full sun are more attractive than shaded or even partly shaded trees.  

If you see EAB colonizing your trees, you can decide whether you want to treat all of them or a portion of them or maybe just a few of them.  You can do it yourself with a soil drench of an imidacloprid product or consider other options. THere is lots of information about protecting ash trees from EAB on the emeraldashborer.info website. Click on "Homeowners" at the top, then click on Insecticides or whatever that box is called.  Or you can use this link:
  https://www.emeraldashborer.info/documents/Multistate_EAB_Insecticide_Fact_Sheet.pdf

Good luck!

Deb