INature: Parasites happen

Ok, 3 weeks behind already. Not sure if I'll have/make time enough to do this INature thing the way I'd like. Oh well...

Parasites are everywhere. Well... there are lots of mutualisms too & they don't get a lot of love, so let's not be too grim. But if it bleeds, it leads, right?

I found this splendid caterpillar near a marsh, munching on some Swamp Milkweed. With the aid of WhatsThatBug.com I found out that it was the Smeared Dagger Moth Caterpillar. Turns out to be a pretty nondescript moth, but I thought it's Latin name was neat: Acronicta oblinita.

I found another one a couple weeks later and decided to bring it home to my daughter.

We had previously cared for a Monarch chrysalis and watched it change from green to clear (it emerged while we were at church).

All was well for awhile. I had found it on a willow sprout and it munched away contentedly. Then we ran into some problems (sorry for the poor pictures... a perennial problem of mine).

 

I detailed them to WhatsThatBug.com:

... It stopped moving completely and even starting spinning a strange web. To my wife’s horror, dozens of small yellow parasites slowly emerged from its side as it was still (apparently?) alive. They all seemed to perish in the hot sun and the ants had a feast. Photo attached. I searched Google Scholar for some clues…

I see a 1903 reference to a ”Rhogas rileyi Cress” being parasitic, mentioning the silk I saw (p. 24 here: http://bit.ly/1atDh3W). However, I cannot find R. rileyi Cress in recent mention so I wonder if the name has been updated. I see a recent publication noting that the parasitic wasp Aleiodes rileyi Cresson often chooses A. oblinita as a host, but it did not seem to undergo the mummification described.

I received a prompt reply:

 ... in our opinion, the parasites that emerged from the Smartweed Caterpillar look more like fly larvae to us, so with that in mind, we would lean more toward this being an instance of parasitization by Tachinid Fly.  We have not been able to uncover any evidence, and that is just our first impression.  Perhaps one of our readers will have better luck determining What Parasitized the Smartweed Caterpillar?

So it was indeed a biology lesson... just not the one we expected! Raising caterpillars is supposedly quite simple. So far, we're about 1 / 5, and that was starting with a chrysalis.