Emerald ash borer has not left Greater Cincinnati.  The number of beetles is down because they've killed the tops of the ash trees in our region.  However, we are seeing a lot of regrowth from stump sprouts and seed germination.  So, as the regrowth becomes large enough to support EAB larvae, we will see a return of threatening numbers of beetles.

This means you will need to continue to treat your tree.  Although we'll never see the huge number of beetles we saw when EAB swept through our region, we will see enough beetles to threaten unprotected trees.

This cycle will continue for the future because the beetles kill the tops of ash trees, not the entire root system if the trees were originally in a healthy condition.  It means we'll continue to see a rise in beetles emerging from regrowth meaning trees must be treated using the original protocols.

However, we're entering unfamiliar territory.  This is the first time anyone, anywhere in the U.S., will experience re-bounding EAB populations.  We don't know if the EAB population will crash again, and we can stretch out the time between treatments, or if the populations will drop to a low level, but EAB will remain a threat.  This means you need to consider the economics of treating your tree as long as you want to prevent it from becoming infested.