This fall is a very heavy nut crop in the woods around here. Some years there are very few, so one had best gather while the gathering is good. We don't have commercial nut orchards, but plenty of "wild" black walnut and shagbark hickory trees to forage from.
I've been gathering, processing, and storing, noting at the same time that most nuts go unharvested. It was this way in the suburbs, where they are often considered a nuisance, but even here in the country there isn't much competition when nut gathering.
The black walnut has a thick, green husk around it while growing, and when nuts first drop from trees, the husk is often still firm and hard to remove. Most people who are aware of black walnuts at all say to dump them in the driveway and run over them with the car, but that seems like a real pain to me. After a while on the ground, the husk starts darkening, even all the way to black, and gets soft and mushy. I found that by just waiting till this happens, the husk comes off very easily, if messily.
What one finds, though, is that the black slimy mess is almost always crawling with some sort of maggots. Looks kind of gross the first time you see them.
Turns out that there is a single fly species, the walnut husk fly, that competes its life cycle by eating on the slowly rotting husk. Now, I find this to be a real convenient collaboration, as the maggots eat and soften the husk, without damaging the nut, and makes my husking operation much easier.
This husk, which the tree expended energy to produce, is now feeding another species, which as far as I can tell, affords the walnut tree no reciprocal benefit. No waste here, nature has found an energy resource and filled the niche. I think the husk, which contains a fair bit of juglone, may act as insect protection, which the husk fly has evolved to resist.
And in yet another commentary on the perverse industrial ag approach to things, nut producers in the west of the U.S. consider this a big problem, to be dealt with by using pesticides to kill the flies. Why? They are concerned about the cosmetic appearance of the shells, which will be darkened by the rotting husks. Some sources I read voiced concern that the dark juice will actually soak in and stain the nut meats themselves, but I have never seen this.
Unshelled walnuts store very well, the nuts themselves are a good source of fats and calories, and are free for the harvesting, so those of you where they grow, what's keeping you from gathering some yourselves?