I purchased some beaver castor liquid, and was just curious how much i should use on my traps? The temp is about 40 to 50 degrees

Who did you purchase it from and what do you mean, "and was just curious how much i should use on my traps?"

I don't know of a circumstance where you'd apply lure to a trap. When applying to a dirthole set, I'd recommend putting the lure down in the hole and on a flat set, I'd recommend putting the lure where the target animal couldn't access it without passing over or through a trap.

I have used Beaver caster down the dirt hole for Fox with good success.

The question has a lot of answers. There are ways to use it properly and ways not to use it.Charles Dobbin's book on beaver trapping would help you. It's only 12 bucks.

Let me see if i can clarify...i bought the lure from an ebay store called Dakotalinesnares and i was wondering how much to apply to my dirthole sets? When i say how much...i mean do i use just a drop? or 5 tsp of the stuff? What would be the most effective ways of using the liquid? Also where can i purchase the charles dobbins book?

It depends on the temperatures. If it isn't too cold in guy, I'd use about a teaspoon full. I normally put a cap full if the bottle has a lid or if it is in a squirt bottle, just give it a squirt down in the dirt hole like you would fox urine on a post set. If it is freeze proof, it should be okay, but if it stays cold, I use a good dose.

If its liquid castor, it is probably tinctured beaver castor. If that's the case, it works best at rub sets, also called projection sets. The canines and cats like to rub on castor.