Monarch Caterpillar under Attack
location: St. Augusta, Minnesota
August 20, 2012
I’m editting photos now, and just came across something interesting. This fifth instar monarch caterpillar may be under attack by a fly.
Although the photo isn’t as clear as I’d like, if you look near the caterpillar’s head you can see what appears to be a small fly. I assume it was attracted to the droppings left from the caterpillar’s overnight binge. I wish I’d noticed it when I was doing the photo. This seems to be a smaller species than the one I previously noted (August 14th).
This has been a very difficult year for the monarchs and other butterflies here; many many predators and parasites and now, drought. The spring was spectacular for bug nuts like me, seeing species not usually seem this far north and large numbers of monarchs on our milkweeds. But it quickly dropped off as we got into the more normal summer season.
Cheers. And thanks again for your incredible service!
Don J. Dinndorf
St. Augusta (central), Minnesota
While we cannot make out details, we can be relatively certain that this Monarch Caterpillar is being preyed upon by a Tachinid Fly, perhaps even the same species of Tachinid Fly from your August 14 submission. What a marvelous addition to our Food Chain tag despite the sorrow of you losing one on your Monarch Caterpillars to predation, or rather, parasitization.
Thanks, Daniel. Next time, maybe I’ll get a clearer shot.
The flies have just been murder here. I lost four metamorphosing caterpillars just today.