Is it illegal to string fishing line on your own trees on your own property?  It should not be...

LOL. Fishing wire is used for many things beside fishing. Once, my uncle was tying up a venison roast for the freezer and ran out of string and used it. Had a horrible time cutting it at the dinner table.

Another useful thing that at least presently has a low probability of being caught using (if you don't do it more than maybe once or twice and don't brag about it) is a radio frequency directed energy weapon. Illegal as hell, because it's essentially a radio jamming device. If the drone has built in autonomy in the event of lost communication, it might just land, at which point you throw a beach towel over it out of sight of the camera, quietly cart it off, and either sell off the parts on Ebay or re-program it and you've got yourself a free drone.

If you use a more powerful EMP type device that can induce enough punch to brick the electronics, then it just falls out of the sky.

While you can't just go buy a military grade anti-drone device like what they use to protect the area around the White House and other sensitive sites, there's enough information leaked out as to how they work that one with sufficient time and knowledge could use that info to build one.

Another way to bring down a drone is with a beanbag launcher rigged with a net. Essentially the thing shoots a mesh net about 200 feet up into the air, with weights that spin to make it fly fully spread out. It hits the drone and wraps around it, and it's all over. The device is normally used to capture individual wild birds in flight without injury.

I haven't heard of a case successfully prosecuted involving fishing line over a yard, but then likely if any incidents involved a drone entangled in the stuff, they haven't been reported.

That is funny. He caught venison.

That would work in an isolated area, but people who love elbow to elbow with other houses could not hide the fact that they are stopping the drone.  They also need to know it’s coming for them.

I suspect illegal drone users aren’t calling the police.

What about a garden hose?

Yes, all wrapped up and ready for the oven. Regular kitchen knives not sharp enough. Had to get one out of the basement.

That’s funny.