terry, i do not know if they work or not but in this video the hunter puts them around his raft so the bears would leave it alone while he was out of base camp. a bear didnt disturb his gear but left him a pile of a present on the exact spot he put his tent. lol
I used them on Kodiak around our meat pole, with zero luck. The bear or bears not only helped themselves to some of my deer meat, but every single mothball I scattered around the area was eaten as well. I can't imagine why a bear would eat them they must do all kinds of things to the digestive tract, none of them good. I used a whole box of mothballs, going with the more is better plan. They were placed around the meat just before dark, and were gone at first light, it's a pretty safe bet the bear ate them before or after tasting my deer. I'm beating a hungry bear really could care less if moth balls are on the scene or not, in fact they may only provide the dessert.
A portable electric fence is a much better plan.