How long would you say castor lasts at a mound set after half inch of rain or how often before you freshen it up… Jon

When i make castor mound sets i always cover my castor with a leaf or piece of bark to help prevent wash away.
You can never have too much castor at a set. Re-fresh as often as you like

I'm no big number beaver man, but I dabble

I would say it depends on the lure. I've ran across a few very runny lures that seem to disappear pretty quick. I also think there are some out there with a very small portion of castor in them. They seem to peter out very fast

Can you still see some lure on your stick? Can you smell any of your castor on the mound?

Take advice from the flat tails themselves. How often do they refresh their mud pies? There you have your answer.

How often do beaver refresh their mounds?

I will be sure to ask them tomorrow morning when I am out checking traps

I’m not a big beaver guy never seen a castor mound on a farm pond just set on sign like feed areas mud on bank some castor on mud and a stick 750 below caught a 42 and a 47 yesterday and an otter this morning… thanks guys … Jon

They refresh territorial castor mounds after a good rain .
Light rain wont wash away a decent beaver lure.
I make a chunk lure for use in spring. Aged black Castor is chopped in small pieces about the size of your pinkie nail.
Black aged castor when done right is rubbery and a small piece has a long lasting and very strong castor smell-use small piece.

I pick Golden rod with the gall on it in the fall. Few seconds with a knife to hollow it out some on the side. A little castor in the hole and stick it in the mud in front of your set. Very water proof this way and blends right in