Mid last month we saw the emergence of Japanese beetles in eastern Iowa. Damage was stronger than ever and the aftermath is all that remains. If you drive through neighborhoods in Cedar Rapids you can see the damage on Linden, Crab Apple and Birch trees. Some of the trees are completely wiped of green leaves and all that remains is the veins on dry leaves. Some trees were hit so hard that it almost looks like fall. Leaves are scattered every where and the trees almost look dead.
If you inspect the ground in some of the local neighborhoods, you can see dead Japanese beetles on the ground. Most of the damage is done by now and there are fewer Japanese beetles flying around. If you sprayed your susceptible plants with an insecticide, you have probably only had to make one application this year because of the lack of rain. There is probably still residual left on your leaves from the application that you made last month. Depending on the insecticide that you used, some of your product may have trans-located into the plant. Trans-location means moving from one part of the plant to another. Even if your insecticide is not on the leaves of your plant, it still may be found in them. Most if not all Japanese beetle damage has stopped on the trees that we sprayed last month.
Insecticide treatment for Japanese beetles.
When choosing an insecticide to treat insects make sure that you are using the right product for the application. If you are treating any edible plants with an insecticide, make sure that it is safe to spray on fruit and vegetables. You do not want insecticide being absorbed by the edibles if you are going to consume them. If you are treating a non edible plant, then it might be a good idea to use a product that trans-locates within the plant.