The Kania trap by far is the most effective way to get rid of tree squirrels without a doubt. If is swift, humane, and extremely effective. They are well worth the investment. Here, in my neck of the woods, we have a terrible, terrible issue with ground squirrels, which worry my Aussies to no end, especially my young boy, who has taken on the mantle of "squirrel killer". That dog has gone through the screen door twice to get at a particularly pesky ground squirrel. Even as wickedly quick as my youngest Aussie is (and he is something else), he is still no match for a gound squirrel in close quarters. So, essentially ineffective. For me, the only way I can keep them down to a low roar, is poison bait stations. No other option, I have tried every single method of control. We cannot have cats outside, due to our very high coyote population here in the hills of Vista (I back an abandoned 147 acre orange orchard that is full of every conceivable wild animal and predator you can name: coyotes, weasels, bobcats, racoons, opossums, red tailed hawks, red shouldered hawks, sharp shinned hawks, white tailed kites, american kestrals, barn owls, great horned owls, rattle snakes, king snakes, garter snakes, gopher snakes, road runners, just to name a few predators.) All of these (and we have a lot of them, seen every day from my windows in multitude) cannot keep the rodent population down. I am using non-kill through bait with great trepidation, as the bait is NOT reversible in my dogs, if my dogs get into the bait, but it saves the predators, while killing the pests. Not only do I have ground squirrels, but I have roof rats, mice, bunnies and gophers, all of which threaten my figs (and other fruit trees). I love living out in nature, just struggle with our very high rodent population.