I have a cherry tree that has a lot of lice every year. I don't like using chemicals to get rid of them, so I've been trying different methods. Last year I frequently sprayed the whole tree (it's a small one) with water to flush out the lice, but they kept on coming. Then I found out that ants are actually partly responsible for the lice, because they farm them. The lice produce a sweet liquid that the ants like, in return for that the ants protect the lice and carry them around. So I figured that if I can get rid of the ants I should also get rid of the lice (at leats partly).
This is a very short and simple instructable which would take less than 5 minutes to finish.
Step 1: The One and Only Step
I read somewhere that ants really dislike chalk, so I took one of my daughters chalk crayons and smeared it on the bottom part of the tree and the pole supporting it. I watched a little bit and noticed that not a single ant crossed the chalk, they all immediately turned around. Make sure you don't leave any unchalked traces, because they will find them. The only downside is that this has to be regularly maintained (put some new chalk).
This method could also be used to keep ants away from other places where they are unwanted.