need ID for webbing cocoons on leaves

9 years ago

Found some leaves eaten and fras under a pot of tomatoes on a deck. l expected to find tomato hornworms - I did not, but may still (it is hot and they could be hiding). It is what makes the most sense, right? But what I did find were these cocoons on a couple of leaves. I'm pretty sure hornworms pupate in the soil, so what could these be? Google is not being helpful, so can you guys provide some insight? Could whatever this is be what has eaten leaves and even parts of tomatoes? Thanks in advance!

Deb

Featured Answer

digdirt2

9 years ago

There are many hundreds of web-forming caterpillars, some good, some bad, as it is a large family. But it is almost impossible to ID them from the cocoon itself IME. All you can do it tell who they are NOT. They are not bag worms or web worms nor any of the common butterflies nor are they hornworms.

So the best bet is to find any of the caterpillars before they cocoon. Have you noticed any? They are what would have done any damage to the plant, not the cocoon itself. So there is no need to destroy them. So I would just remove the leaf from the plants as you find them and place them away from the garden where they can cycle normally.

Dave

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Comments (12)

cloud_9
Original Author
9 years ago
I haven't found any cats at all - just the 3 cocoons. I swept up the frass and will see if any more appears. Maybe the three culprits are all there were. That would be nice. I had no intention of killing them.
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Jean
9 years ago
Perhaps caterpillars that were parasitized by a tiny wasp, Copidosoma?

See http://bugguide.net/node/view/368676
Jean
9 years ago
Well? Does it match?
gorbelly
9 years ago
I don't think the OP has any way to know whether the caterpillars have been parasitized by copidosoma wasps without seeing the caterpillar itself, and cloud_9 has said there were no caterpillars visible.
gorbelly
9 years ago
One of the most common caterpillars that weave these kinds of cocoons are loopers. http://bugguide.net/node/view/893895 And they are common pests on a wide variety of garden plants. But, as Dave says, it's impossible to tell for sure without seeing an actual caterpillar or pupa.
Jean
9 years ago
last modified: 9 years ago
When I gardened in SoCal for 30-some years, I often found that cabbage loopers were parasitized by Copidosoma. The S-shape is typical for that combo.

In any event, that garden has a case of active bio-control.

Nice, right?
gorbelly
9 years ago
Yep! Summerlee recently got a good pic of one.
cloud_9
Original Author
9 years ago
Sorry for the delay - I was getting ready and then traveling. Whatever the cats were, I never found any more than the three cocoons and no more frass. The area of defoliation was relatively small considering the damage that could have been done had it been hornworms. I have placed the offenders in a container to await reemergence. My curiosity always wins out. I garden organically and there is much biodiversity here, despite the huge amount of invasives that we are working to eradicate (recently moved), so that would be nice if they were parasitized, Thanks for all your help. I will post pics when and if they emerge so your curiosity can be satisfied too! : )
Jean
9 years ago
Hope you have them in a clear, covered container. the cover can be as simple as a piece of paper toweling rubber-banded in place.

The Copidosoma will be numerous and very small.
cloud_9
Original Author
9 years ago
clear container, dining table so they are where they will be seen. I'm not home right now, but my husband is keeping an eye on them and I will tell him to be on the lookout for the possibility of tiny parasitic wasp babies. I hope they don't hatch/emerge until I am back! : )
Tricia McAllister
6 years ago
What did they end up being? I have what looks identical on one of my tomatoes right now!