Square Headed Wasp takes down Drone Fly

Subject: Predation
Location: Sussex County, NJ
July 31, 2017 8:44 am
I witnessed a square-headed wasp (Family Cabronidae, I believe) take down a large syrphid fly this morning and thought I’d share the photos. Also, wondering if you might be able to narrow down my ID on the wasp for me?
The attack was remarkably fast with the wasp landing on the fly and quickly subduing it. Eventually the wasp dropped the fly as it seemed that it was too large for the wasp to carry more than a very short distance. Interestingly, an hour later, the body of the syrphidae was gone – so did it recover or did something else come along and dispose of it? Fascinating.
Signature: Deborah Bifulco

Square-Headed Wasp and Drone Fly Prey

Dear Deborah,
Thanks for sending in your amazing images that are greatly enhanced by your written observations.  Speculate is the best we can do for the subsequent exploits of the Drone Fly, but we can be certain that it was alive after the encounter.  We would like to speculate that after that spectacular attack, the Square-Headed Wasp partially glided, and partially dragged her prey to her nest to serve as fresh meat for her developing brood.  Of the Square Headed Wasps in the subfamily Crabroninae, BugGuide states:  “Some nest in hollow stems or in abandoned galleries in wood, others burrow in the ground. Prey is mostly flies, but some utilize other insects.”  Exactly a year and two days ago, you submitted a very similar Food Chain image. that appears to be of the same species, both predator and prey, and at that time, we identified the genus as possibly
Ectemnius.  We will look into this more thoroughly.

Square-Headed Wasp and Drone Fly Prey

Hi Daniel,
Thanks so much for your very informative response!  And forgive my senior moment in forgetting the photo I sent to you last year.
I actually wondered if the wasp had just paralyzed the Drone Fly, or if it was dead.  But it certainly makes sense that it would be alive, especially as it would be a food source for the wasp-kids.  I have a small colony of Great Golden Diggers and frequently see them carrying very large katydids into their nests.
I have found with insects that the more I learn, the more I want to know.  J

You are most welcome Deborah.  We can always depend upon you to send in great images.

Square-Headed Wasp and Drone Fly Prey
Square-Headed Wasp and Drone Fly Prey

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