Last week we saw the first signs of Japanese beetles this season in eastern Iowa.  This week Japanese beetles were out in full force.  I drove by several properties with crab apple and fruit trees on Monday that looked normal.  Today I drove by the same trees and they were completely devastated.  A majority of the foliage was gone with only veiny remnants remaining on what were the leaves.  Dead leaves scattered the ground below that were once fully leafed specimens last week.

Japanese beetles feeding on leaves.

Japanese Beetles

 From what I observed, the Japanese Beetles started feeding at the highest point on the plant and worked their way down from there.  After a closer inspection of some of the trees, I noticed up to twenty beetles on a two inch leaf.  The feeding that I have seen in past years was nothing like what I saw this week.  In the past there were only a few Japanese Beetles on each leaf.  This year it looked like there were not enough leaves to go around. 

Since we had a milder winter last year, it is safe to say that the milder temperatures helped create this problem.  It seems if though there are more Japanese Beetles this year than last because of the lack of ground freeze.  Japanese beetles were able to reproduce quicker and by more numbers this year because of the lack of winter.

It is now more important than ever to treat your susceptible trees and plants with an insecticide.  Depending on the weather it might be necessary to treat your trees and plant multiple times this year.  Most insecticides will kill briefly after contact and any residual left on the foliage of the leaves will kill late comers.  We treated several trees this afternoon and within minutes, the trees were completely free of Japanese Beetles.  It is important to monitor your plants after an application to make sure that you covered all of the foliage on the plant.