Homemade Tarantula Islands are Lucrative, but Terrifying
I just returned from a mystery island I spent all evening on and I just quit playing for tonight, but I managed to bring back 33 Tarantulas, 2 Sturgeons, and a Stringfish.
I watched a video on YouTube that demonstrated how to make a Tarantula island. Following the steps in the video, I removed all the trees, plants, and rocks on the mystery island. After I did that, the only bugs that appeared were Tiger Beetles, Wharf Roaches, and Tarantulas. I spent all evening shooing away the Tiger Beetles and the Wharf Roaches, but the Tarantulas would appear fairly regularly. I ended up leaving behind all my tools, except my bug net, in order to bring back as many Tarantulas as I could.
I estimate that, nestled in my spare room, I probably have about 285,000 bells worth of *very* disturbing livestock to turn over to the Nook Twins tomorrow morning.
Notes: Take a metal axe with you to the island, but leave behind your slingshot and watering can. Get the resources from the stones *before* you break them; you'll need the iron to replenish your tools, but in a pinch Wilbur will sell you flimsy tools for a decent price. Chop down all the trees, including the coconut palms. Dig up all the stumps. After you've denuded the island, empty your pockets of all but the most necessary of items (net, vaulting pole, ladder, maybe fishing pole) and dump them onto the beach. Don't dig up the flowers, just pluck the blossoms and dump those on the beach. I pulled all the weeds too, mostly to make it easier to spot the Tarantulas, but I don't know if it helped in any other way. Only try to do this on islands with one or two levels, anything more would be too difficult, I think. Accept that you will get stung. I got stung 5 times, each time waking up on the dock next to Wilbur, with no apparent lasing ill effects. Tarantulas don't come out until after 7 pm. Each Tarantula is worth 8,000 bells.
The preparation takes some time, but I believe it is worth the effort. That being said, I don't think I want to spend every evening hunting Tarantulas; I moved to a deserted island to try to relax, not to reenact scenes from the movie "Aliens" ("It's a Bug hunt, man"). But to those dissatisfied with the bell-making opportunities on their island, I offer this strategy as an alternative to the traditional fishing, bug catching, and tree shaking.
Good luck to those brave enough to try this.