Scare away giant water bugs

If you're lucky and land on Bamboo Island, islands with ponds and water bugs seem like a lost cause to me.
Although time consuming, do the typical farming setup: remove all trees, flowers, and rocks. Then dig up all the grass - this prevents multiple Mole Crickets - except for a square like the on in the picture below. And one line, for running to the rocks, on the back row. Bugs won't spawn in small areas like this. Then run to rocks, scare Wharf Roaches, return to your square, where there will either be Tiger Beetles or Tarantulas, repeat, and get bells!
Tried for an hour without digging, only got about five. 30 minutes with digging, and I had a full inventory, and had to drop tools.

The only way to get rid of giant water bugs is by catching them with a net and releasing them.

They don't despawn when you run near the water's edge, use your vaulting pole or ladder nearby, or by using a fishing rod on top of them. Unfortunately, I've had to bring two nets at least to every island to account for them. They sell for a fourth of the tarantula pricing, clocking in at 2,000 bells compared to 8,000 bells, excluding Flick. He's at my island right now as I'm grinding, so we are in the exact same boat, my man. Best of luck.