Because the emerald ash borer is so destructive, it is very interesting to know that our recent very low temperatures may have been beneficial (from our native ash trees' perspective) in killing off some of these insects. The negative temperatures weren't quite as low in Michigan as they were in Minnesota and Wisconsin, but studies have shown that air temperatures of -34 C (-29 F) kills over 93% of borer larvae.
It will be interesting to see the results of any surveys or studies of emerald ash borer populations conducted over the next year!
Also, this is a good time to mention that one way these insects spread when people transport firewood, which is why you should never bring wood from home elsewhere, for campfires or bonfires or the like! Buy wood locally when you plan to make a fire.
EDIT 1/11/14: The NPR radio show Science Friday covered a segment on this, plus other invasive pests. Check it out here: