Interactions between Megarhyssa macrurus ssp. macrurus, long-tailed giant ichneumonid wasp and Tremex columba, pigeon horntail, and on a sugar maple tree on July 8, 2023, at a Barnes Prairie hedge row, Racine County, WI

Walking along a hedgerow adjacent to Barnes Prairie on a humid, 82F degree late afternoon on July 8, 2023, I heard a “clacking” sound. In the hedgerow, I saw a long-tailed giant ichneumonid wasp on the trunk of a sugar maple tree, which appeared to be making this noise. The possible reason for her agitation seemed to be a second long-tailed giant ichneumonid wasp, which had come into view on the tree trunk. When it appeared, the first ichneumonid wasp ran towards it. The second ichneumonid wasp flew, but from my vantage point, I could see it landing on the back of the tree trunk.

The maple tree that these ichneumonid wasps were on had a trunk diameter of approximately 24 inches, 6 feet above the ground. There were several dead branches on the tree, however; about three-quarters of the branches were leafy.

I turned my attention back to the first ichneumonid wasp. She was walking, then “freezing” and I became aware of a pigeon horntail, seemingly oblivious to the ichneumonid wasp, which was about a foot from her. The pigeon horntail was walking around in a small area below the dead branches, stopping periodically. The ichneumonid wasp began to slowly arc back and forth around the pigeon horntail. From time to time, the second ichneumonid wasp appeared on this side of the tree. The first ichneumonid wasp either ran towards it or flew at it. The second wasp flew or ran around the trunk of the tree, out of view.

For about a minute, the first ichneumonid continued to walk back and forth at the sides of the pigeon horntail, at a distance of about 3 inches to over 12 inches, “freezing” when the pigeon horntail moved. The pigeon horntail found the spot she was looking for and began laying eggs in the tree. After a short time, she flew off. The ichneumonid flew away a few seconds later.

Was the ichneumonid wasp’s interest in the pigeon horntail to mark or remember this area, which with an eye to revisit it at a future date? I made my rounds by this tree several times after July 8, but didn’t see any giant ichneumonid wasps or pigeon horntails on these trips.

I had photographed a giant ichneumonid wasp on this same tree trunk, about 6 feet from the ground, on June 29, 2023, in an area a few inches away from where the pigeon horntail had laid her eggs on July 8. I watched as the ichneumonid landed, and head and antennae down, walked along the bark of the tree, possibly detecting the smell/movement of pigeon tremex larva. After about a minute and a half, she began laying eggs into the tree trunk. Her efforts took about 5 minutes (about 5:06 to 5:10 PM), then she flew away.

I have numerous photos of these two wasps, not included in this journal entry. Contact me if interested in seeing them.

Publicado el 17 de noviembre de 2023 a las 11:49 PM por bkis