I don't know if this is quite so off topic.
Pooh was making a sly hint at some other uses of formic acid, and thusly the type of places where it may be sourced..
Interesting to note that you can identify nylon using formic acid, because it is soluble in such. Also interesting to note that carpet is made out of such a material, nylon, and test kits exsist to help carpet inspectors to determine what type of carpet they are working with.
PB
I don't think any particular source was mentioned; just a route of acquisition. Hey, pretty cool, I just rymed! :P