About 6 feet deep at the deepest end, and you should back the combine in. Actually mothballs as mentioned earlier, in the shoe augers, clean grain and return auger troughs, elevators, feeder house and grain tank are probably the best solution if you can't get them poisoned before they find the machine. Question about mothballs, though. Do you gather them while the moths are still caterpillars, or do you wait until they sprout wingsIJ I'm also not that good with a knife -- do they make rubber bands that smallIJ