Animal Crossing: New Leaf: ULTIMATE MONEY GUIDE!

This guide was found from: http://www.animalcrossingcommunity.com/Topic/5787432/1/

Access to the island.
Needs to be 5PM or later.
To start, cut down ALL the trees, except for two palm trees. make sure they're on opposite sides of the island so you can run between the two palm trees.
Dig up the stumps of the trees you cut down.
Pick two flowers and plant one in front of both palm trees.
As for the tools, you need an axe and a shovel, but both are loaned to you for free while you're on the island.
Once this is set up, get a net, and give back the axe and shovel so you have an empty inventory (Besides the net which isn't in your inventory while it's equipped.)
To efficiently catch bugs, swing towards the tree when you right behind the flower, and hold A to sneak with the net. (Once you release A, you'll swing, just a heads up.)
Now go between the two trees (Keeping a safe distance away so you don't scare the bugs off.) and scare off any other bugs (Because bugs have a spawn limit. If scaring away other bugs absolutely doesn't result in beetles coming back, go inside the hut and come back out.)
Enjoy rolling in money as you sell off all the catches!
12,000 bell bugs:
Golden Stag (Be very slow when sneaking up on this one. They fly away easily. Just barely move the control forward.)
Horned Hercules (Same as Golden stag. Flies away easily.)
10,000 bell bugs:
Giant Stag
Rainbow Stag
8,000 bell bugs:
Cyclommatus Stag
Horned Atlas
Horned Elephant
6,000 bell bugs:
Goliath Beetle

Final note: That guide recommends having the Wealthy Ordinance, but I easily made money without it.