never heard of it being done, but seems like it's probably good stuff. Don't know the first thing about caterpillar poop, using it is a new one on me. But, if ya got it...

About 30 years ago there was an invasion of gypsy moths in my area that generated so much frass it sounded like rain pattering down on the trees - all day long. (Having picnics outside was not a good idea.)

The grass grew fabulously.

Go for it.

I work in a laboratory, so I think I will do at least a nitrogen analysis, and maybe the P and K. I will post them when I find out. There are several large butterfly breeders in the US, who knows.

Would love to here about it and can't imagine that it would do any harm. Poop is Poop and being plant based it just gotta be good you would think.
Let us know what you find out please.
Happy Growing David

end3,

That would be fabulous if you could analyze the content, then get back to us with the answers.

end3,

Have you had a chance to do the analysis as yet?

I'm very curious because I teach entomology to the local Master Gardeners and it would would be a fun did-you-know comment!

I am going Saturday morning, I changed jobs from an environmental lab to a QC lab for a manufacturing plant. My old lab has the instrumentation to do a nitrogen analysis and I am still doing a little consulting for them. I will try and post Saturday afternoon. I am hoping for a high N, but am not optimistic as most poops are not very high in N if I am not mistaken. It is kind of unique and I think it would pass OMRI if one could gather enough volume. :) I have not forgotten. Thanks for asking.
Ed

Interesting! What kind of butterflies does she raise? It seems the quality of the poop might depend a lot on the host plants. Both the type of plant and its health/nutrition status. And if the host plant is toxic to most animals, such as milkweed, the poop may have insecticidal properties as well.

Sorry, no result yet, left the bag of frass on the counter Sat. morning. She raises eastern black swallowtails, they lay and feed on dill, fennel and parsley. Don't know the NPK of those plants, but I have seen a little reseach saying the butterflies get bigger with more protien. Don't give up, I am still going to do the nitrogen.
Ed

If I recall correctly, dill, fennel, and parsley are all known for extracting minerals from the soil (they all have deep taproots), so I imagine it could be rich in P, K, and trace elements.

Remember too that anything that increases humus in the soil will favor nitrogen-fixing bacteria, among other beneficial organisms. So even if the N analysis comes out low that might not be the whole story.

It would be interesting to compare potting mixes made with caterpillar frass to similar mixes with worm castings and/or compost.

Well? Have you analyzed the frass as yet?

Curious folk want to know!
:>)

The caterpillars eat, mostly, the young, nutrient rich, growth of plants so it stands to reason that the frass they generate would be a fairly good fertilizer. Those caterpillars would use a fair amount of the Nitrogen to make the protein their bodies need to grow so a high amount of N probably would not be present although at the speed they do eat they may not be able to process all of what is available. I have found only references to this frass being a good fertilizer for the plants, nothing about the analysis for specific values.

Curious to know if caterpillers that eat plants cintaining atropine(angel trumpets,moonflowers..etc.)would transfer any toxins if using their frass in soi"!! Im raising some very cute n fuzzy yellow wooly bears and have alot of their poop ive been throwing away.would love to b able to recycle it!!!

I have two massive oaks being eaten and after it rains there is a thick mud of there poop id like to know if I can save it as a fertilizer I would assume its like worm castings

Insect Frass - Insect Frass 2-2-2 is an organic fertilizer and soil amendment derived from the excrement of herbivore insects, providing high quality nutrition for plants and soils.

zk....it would make a great deal of sense to leave the frass right where it is and allow the oaks to get some use out of what has been taken from them by the caterpillars. Massive trees have a great need for nutritional support in their declining years.

And again a reminder

USPS website says: