Revretch I am back with more made up bio questions, what would it take to make a beetle (true beetle!) to be like, a MASSIVE threat of an invasive species across all environments but its own native island? Basically I have this beetle that eats a lot, but on its own island this isn't an issue because the grubs are eaten up when they're still in the ground and population is kept low. I wanna know how I could make this the most fucked up invasive beetle possible because it's extremely useful for medicine which has created a black market for it, and I think as dungeon master I can have my players do a lil environment mission, as a treat for me
Well, it's not just a matter of how much it eats, it's a matter of what it eats. Any important crop--or several--being targeted by a particularly prolific beetle spells trouble.
The khapra beetle is one of the 100 worst invasive species in the world. It infests all kinds of grains, cereals, rice, dried beans, seeds, etc. etc. It can survive long periods without food or water, and is resistant to many insecticides. It can also cause horrible allergic reactions.
It's also a matter of how prepared the people in those environments are for it.
Before pesticides, boll weevils were a tremendous problem (and still are, though to a lesser degree). The effects of their devastation of cotton crops decimated much of the American South's economy and substantially altered American history. Even now, according to Wikipedia, 90% of Brazilian cotton crops are infested by them.
There's also the Colorado potato beetle. After WWII, nearly half of all potato fields in East Germany were infested by it. Again, pesticides helped. (Though, of course, at a horrifying environmental cost, but that's another discussion.)
So, really, you just need to figure out which crops are the lynchpins of your setting's societies, and have the beetle pull that out from under them. Being as invulnerable as the khapra beetle is a bonus. For extra tenacity, you could even make its diet as diverse as the mealworm's--they can get by on styrofoam.
