A web-based mystery

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leonardturner
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Joined: Thu Mar 14, 2013 11:40 am
Location: Atlanta, GA, USA

A web-based mystery

Post by leonardturner »

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My wife first noticed this structure, 22mm in height, hanging from the top of an open walkway, and wanted it removed. It is shown here inverted on a small pin.


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The elongated conical structure proved to be composed of numerous individual components, about 2mm in length, held together by an internal mass of web material.


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Cutting and crushing some of the individual components and examining them at 4X with a microscope showed no obvious internal structure, and I thought this most likely frass, although why it should be so organized was a mystery.


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Returning to an earlier stack, done a few days earlier when the item was fresher, I remembered seeing what looked like small cream colored ovoid structures--possibly eggs, and reviewing this image there is an interesting honey-comb arrangement of cells which might have contained such, so my current belief is that this represents a group of egg cases. If so, of what type? Spiders frequent this area, as do moths of various sorts, but I've not been able to find anything like this described.

Leonard

MarkSturtevant
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Re: A web-based mystery

Post by MarkSturtevant »

That is a weird thing. It is a sausage of frass (poo), adhered to the outside of what looks to be a cocoon, I guess. Is there a pupa inside?
Mark Sturtevant
Dept. of Still Waters

leonardturner
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Re: A web-based mystery

Post by leonardturner »

Mark, an excellent suggestion. Unfortunately, nothing inside except the supporting/unifying web. I cut and crushed a few more of the component parts for the microscope, but could see no consistent structure in any of them. I wonder if anyone else has seen anything like this, or could point me to somewhere to look for an explanation.

Thanks,

Leonard

AlP
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Re: A web-based mystery

Post by AlP »

Possibly a type of bagworm moth.

MarkSturtevant
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Re: A web-based mystery

Post by MarkSturtevant »

leonardturner wrote:
Sun Sep 25, 2022 8:30 am
Mark, an excellent suggestion. Unfortunately, nothing inside except the supporting/unifying web. I cut and crushed a few more of the component parts for the microscope, but could see no consistent structure in any of them. I wonder if anyone else has seen anything like this, or could point me to somewhere to look for an explanation.
Thanks,
Leonard
If I am right, I expect the pellets you are examining is insect poo. Either from chewed leaves or wood. The silken cocoon they are attached around could be empty if the insect emerged and the shell of the cocoon dropped out of an open end.
If I understand correctly, you found spherical objects inside one of the pellets. Assuming those are tiny, those could be the husks of pollen grains.
BugGuide is awesome (https://bugguide.net/node/view/15740). A search for "cocoon" turned up up some similar objects which are cocoonsr: https://bugguide.net/node/view/1191349 and https://bugguide.net/node/view/1091423
Mark Sturtevant
Dept. of Still Waters

leonardturner
Posts: 713
Joined: Thu Mar 14, 2013 11:40 am
Location: Atlanta, GA, USA

Re: A web-based mystery

Post by leonardturner »

My thanks to you both. There was no sign of remnants of a cocoon inside what now appears to have been simply a hollow column supporting the dozens of particles framing the outside. Perhaps whatever gave it the elongated ovoid shape has been lost, but where or how is a mystery. I will pursue this in bugguide as suggested.
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This is what I found when I split it down the middle and spread it apart--nothing.

leonardturner
Posts: 713
Joined: Thu Mar 14, 2013 11:40 am
Location: Atlanta, GA, USA

Re: A web-based mystery

Post by leonardturner »

OK, after a couple of days pawing around on Bugguide, I believe what we have here is what I have seen referred to as a frass retreat or frass shelter or something closely related to that. Some insects, bagworms are mentioned, form nests or cocoons of frass, a rather strange but apparently effective concept.

Incidentally, Bugguide has a main heading named "frass"; hoping to find a quick solution to my question, I went there only to find that it is actually a dumping ground for photographs that don't meet their esthetic or other standards, and where doomed pictures live for a month until they are deleted. This has even generated a verb form, as in to "frass" an image.

Leonard

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