Island layout for beetles

What's the best layout for my island to spawn beetles? My girlfriend visited my island and cut every tree down and there was nothing lefti

You can plant about 4-5 palm trees (coconut or bananas) on each side of the island. You'll have to sneak up to the beetles to catch them so having them on the side vs. on the bottom makes it easier for you to see them. 4-5 fruit trees in the middle to spawn rainbow, giant stag, and scarab if you care for them. I think the spawn rate is just random regardless of where you plant your trees.

How do I get trees onto the island?

you can go on tours on the island by talking to Leilani; most of the tours will have lots of trees and you can just snatch a few fruits; you can even bring the fruits back home

I know other's have already given advice, but sometimes a visual can help.

So, I just doodled up a generic map for the island setup. If you're looking for the other bugs too then plant some trees in the middle.
(I usually just catch the palm tree bugs, so I didn't draw any middle trees.)