This usually means there's a nest alongside the trail, right? I made up some warning signs and set out to try and find the nest, inching down the trail looking for wasps, especially at ground level. Wasps often have a ground nest right next to a trail. Instead, I found a black birch tree swarming with wasps. This tree leans into the trail and is hard to avoid. Terry had walked right through a cloud of wasps.
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This family was alerted by the warning signs
and trying to decide what to do. |
I figured there must be a nest in the tree but couldn't figure out where the entrance was. We will go out at night and spray a nest if it's right next to a busy section of trail and people are getting stung, but you need to know what to spray. There was once a big nest of Bald Faced Hornets hanging over the Rec Path off Lane Street and the hornets were stinging anyone who just happened to walk down the path. We lugged in a ladder at night and sprayed the nest. For this tree, I needed to come back with some binoculars and leave the dog at home. So I did that the next day.
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| Bald Faced Hornet, yup |
I hung around for about twenty minutes studying the waspy tree with binoculars. Mostly there were Yellow Jackets, but there were also a few Bald Faced Hornets. The tree was a Black Birch, also known as "Sweet Birch" due to it's copious sweet sap, and the trunk was full of holes made by Yellow-Bellied Sapsuckers. These are small black and white woodpeckers that create a line of holes in trees so that sap oozes out of the hole. They drink the sap, as do many insects, and will return to eat some of those insects and drink more sap. Most of the holes were old, but there were a couple spots with raw wounds oozing sap, and this is where the wasps were landing. The larger Bald-Faced Hornets were greatly outnumbered by Yellow Jackets but were still monopolizing the oozy spots. The Yellow Jackets seemed pretty agitated about this and were zipping about the tree trying to get some sap.
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| Old holes and an ongoing tree wound oozing sap |
I tested out my working theory that these wasps were just foraging and didn't have a nest there by putting on a thick protective layers of clothing in the 90 degree heat and spraying the tree with permethrin (the same stuff I use to treat my clothing for ticks). I started by hitting a pair of feeding Bald-Faced Hornets directly to take out the most dangerous players first, and after a minute or two all the wasps had disappeared. There was no nest. They wouldn't have left if there was a nest.
I hoped the permethrin would keep them away, but a day later the wasps were back, with new sap oozing out over the areas that I had sprayed. I returned with some tree pruning sealer spray, but the sap gushed right over it (the dark areas on the tree are from that spray). It did help to show which areas were still active.
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| Sapsucker holes oozing tasty sap for the wasps |
During one of my checks, the guilty pair of Yellow-Bellied Sapsuckers mocked me. Both were in the tree. Probably laughing. One was actively feeding from the tree wound near the blue blaze.
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| A pair of Sapsuckers on the tree |
The latest plan involved covering up the oozing spots with a layer of sticky Tanglefoot, then sticking some plastic sheeting to it like a bandaid, followed with more plastic sheeting with more Permethrin spray underneath. No idea if this will work. Will the woodpeckers try to peck through the plastic?
At any rate, if you come upon the warning signs, keep your eyes open. If the wasps return and are swarming the tree, either slip by quickly and quietly, or head off-trail and keep your distance. They are mostly like the Yellow Jackets that pester us during a picnic, but all it takes is a few Bald Faced Hornets in the mix to liven things up.
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| Sticky Tanglefoot over the tree wounds |
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| Plastic over the sticky Tanglefoot |
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| And more plastic |
Update 7/10: So far, so good! No wasps today.
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