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Project Noah Nature School
Heterocampa guttivitta
I am sad to spot this caterpillar because this creature was struggling to chase the ant off from the sac she was holding (I believe this is an egg sac?) The caterpillar kept swing its body around the sac to chase the ant off from the sac (please see the video), but it was no avail. I went back to the same place next morning. Sadly, this caterpillar was dangled down from the plant and it appeared to be dead. I think she spent all her energy out to fight the ant to protect the sac. It was very sad to see it. Or, maybe I am all wrong.....
Thank you so much again for further information. I am truly overwhelmed by witnessing this. Life is hard, but insect world is even more. Amazing……
Interesting! Here's another link to a similar behavior by a caterpillar:
http://www.projectnoah.org/spottings/209...
@Jakubko: Thank you very much for ID and more information.
It seemed the caterpillar was attached or did not want move or could not move from the sack. It was there the entire day and the next morning, I walked back and I found it in exactly the same place. As I described in my note, the caterpillar was dangled down from the same plant and it was not moving.
John is correct, the "ant" is a parasitic wasp in the family Ichneumonidae. Here is a short snippet of some research done on the parasites of H. guttivitta: http://journals.cambridge.org/action/dis...
The large black spots on the side of the caterpillar are due to parasites.
This is a shot in the dark, but perhaps the parasite of H. guttivitta is similar to the behavior of Coleomegilla maculata and Dinocampus coccinellae which is well exhibited in Karen's spotting:
http://www.projectnoah.org/spottings/313...
Did the caterpillar seem physically attached to the caterpillar as if it couldn't move itself from it?
John La Salle: Thank you very much for your kind explanation and website. It is really interesting... I am not sure if I would try to open the sac, but if I become too curious, I may try it. And, if I do, I will report the result to you. Again, thank you so very much for your kind comment.
RiekoS. Very nice series - and I am not exactly sure what type of behaviour is going on here, but it seems pretty cool.
First, not sure what the sac is - but it is not a caterpillar egg sac because the caterpillars are not mature (reproductive) adults and thus aren't capable of laying eggs. That leaves three possibilities: 1) the sac contains parasites of the caterpillar which have emerged and spun up cocoons underneath the caterpillar, and left the moribund caterpillar weak and near death (I have seen this many times before, but never with the cocoons enclosed in the sac-like structure you see here), 2) the caterpillar just happens to have wandered onto the egg sac of some other creature such as a spider egg sac, 3) some other weird biology that I have no idea about.
As to the "ant" in the pictures - it is not an ant, it is a parasitic wasp. If you look closely at the video you will see that it is sticking its ovipositor (a thin egg-laying tube) into the sac - probably in an attempt to lay eggs on whatever is in the sac. I am not sure what this is, but I suspect it is a wingless Ichneumonidae. Just as an example, here is a link to a wingless ichneumonid that parasitises spider eggs as well as the cocoons of other parasitic wasps
http://bugtracks.wordpress.com/2011/07/1...
As a suggestion, just toss the sac into a jar with a bit of paper towel to prevent condensation and see what comes out.
Spotted on Aug 10, 2013
Submitted on Aug 15, 2013
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