Caches are very often hidden in hollows. Generally any tree with more or less visible hollow is a very probable geocache hide.
Often you can't easily look into that hollow because it's deep or located above your head. I usually simply put my hand into the hollow to check what's inside. In Central Europe the danger is relatively moderate, in worst case you can be bitten by squirrel or maybe wild cat. But in some countries, like Australia, there are very dangerous spiders and even protective gloves won't be enough.
Are there any safe methods to check in hollows for cache, without risking being bitten?