On Monday, June 11th, TJ shared some leaf samples he had collected in the field. These leaves were marked with feeding damage from a small black insect he also had collected to show us. I had never seen or heard of this critter before that day, but TJ's sharing could not have been more timely. Since then I have had the opportunity to see evidence of plant damage by the Yellow Poplar Weevil from Ostrander to New Albany.
Here at Russell Tree Experts we have had an ongoing conversation about how to treat this pest, and if treatment is necessary. I did a little research initially and confirmed what TJ had shared with us: the insect has only one generation per year, and the damage to the leaves of Tulip Poplar, Magnolia, or Sassafras trees is mainly aesthetic and does not require treatment. This is to be contrasted with a spider mite infestation, for example, where multiple generations can cause a huge outbreak in a short period of time causing great damage to a plant.
This information was consistent with what we found in the field that week. The following week everything changed, when TJ and I went out to inspect a young Tulip Poplar that had been in the ground for about a year. From a distance my first thought was that the tree had not been watered, for every leaf except a few in the inner canopy looked completely brown and dead. When we walked up to the tree we were amazed to find the largest population of Yellow Poplar Weevil we had seen to date. They were so numerous that the adult feeding damage had almost completely browned out the leaves. As TJ went for the garden hose to try to spray the weevils off, he realized his fluorescent green Russell Tree Experts T-shirt was covered in weevils. They either liked his shirt or his aura (or his odor?) because I was left out of this meeting between arborist and insect. This was good. Not so good when TJ helplessly let out a yelp when one of the weevils bit him on the back of the neck. This was something our research had not warned us about! But as I look back I think the bite was friendly. Or romantic.
After we realized the hose was not going to get rid of the clouds of flying adults, we made the decision that with serious outbreaks like this one, the best thing to do was to apply a topical spray to kill off the adults. This we would follow up with an application of a systemic insecticide next spring labeled for weevils in case we should have a second outbreak next year.
Presently I think the damage has been slowing down as adults prepare to descend back into the duff at the base of the trees. I have been an ISA Certified Arborist for 9 years in the Columbus area and this is the first year I encountered this pest. Indeed, TJ told me he had spoken with a couple of older arborists who remembered an outbreak "around 20 years ago", and "a long time ago".
Here is a helpful link to read up on the insect if you have been seeing this in your landscape:
http://bugs.osu.edu/bugdoc/Shetlar/factsheet/ornamental/FSyellowpopweevil.htm
Points to Remember:
IMPORTANT: Though TJ claims he was bitten, these insects are not known as biting or stinging insects. I have handled them many times, had them drop onto me from trees, and have never suffered any harm. TJ's experience was special. Weevils are not really evil. Or romantically inclined.
Only one generation per year, so what you have now is all you will get.
Damage is usually minimal, and does not require treatment.
If population is high for your plant, a topical spray is recommended to kill the adults. Spring follow up with a systemic may be recommended in case we have another outbreak next year.
Call Russell Tree Experts for any questions related to this or any other issue with your trees!