I had a flock of sheep for several years and used lots of the raw wool to insulate with. I was worried about insect colonies like wasps and bees but no problems after several years, even where the wool is accessible to the outside environment. The price I received for raw wool was so low it saved money to throw it in the swamp rather than transport it to the woolmill.

Here's the fist hit Google gave my for cordwood masonry . I've seen it used around TF structures, and it's a really cool look. CB.

This is what I will be using for my TF.
Styrorail
Something similar can easily be made DIY but I'm fortunate to have the manufacturer in my back yard.
Cost is $3.17CDN per square foot.
8" wall R25.

Cord wood masonery can have a whole lot of tech problems and should be well researched. It does look cool ,but when wood end grain is exposed to the weather it rots. Unless fully seasoned and peeled it shrinks causes miles of air leaks. If seasoned rot resistant wood is used it would make a solid semi insulated wall probably not sufficient for cold climates. The masonery would be the weak link as it would transfer heat like a son of a gun. Maybe with a thermal break in the center like saw dust , cottn or hemp would boost it's r value. I read once it takes about 2 years , indoors for cord wood to season sufficiently to use

I know this sounds a little crazy, but how about used packing peanuts? And ground up stryrafoam? I seem to end up with more peanuts than I can use from packages recieved or packages recieved at work. They are free. Many products today are also shipped with foam-especially electronic producs. Coudn't this stuff be ground up and blown in for insulation? It should last a very long time and have good insulation properties. Someone would have to do some tests to determine Rvalue though and how thick a wall cavity you would need to get the proper R value. Like I said I come across this stuff all the time and they use it for coolers etc. Sure application might be a little messy or alittle more cleanup in the house, but jeez, it could be free other than the work to collect it. You could also advertise in your town that you recycle this stuff and get people to drop it off to you, no? It's a solution to keep it out of the landfill.

As long as your packing peanuts are the older type... A lot of shippers are using the starch based peanuts these days.
One hair brained idea I had for the attic was to throw all the cut off ends of SIPs into a wood chipper and blow them into cavities.

DO NOT put packing peanuts into your wall cavities until you have experimented with their flammability, and satisfied yourself that the risks are manageable and acceptible.

Shredding polisyinurate makes it out gas formaldahyde or something. Smells like crap when you cut it even.