A nice weekend read that doesn't smell like AI but if you're short on time or interest:

Though the locusts had a huge migratory range stretching all the way to the eastern seaboard, its reproductive range was only a handful of river valleys in Wyoming and Montana. Once plowed, irrigated and trampled by livestock the species had nowhere left to lay eggs.

This answers the title question but the most interesting part about the article is the fascinating way in which the locust’s behavior is triggered by crowding. An amazing biological adaption.

It’s well-worth reading the whole thing.

I immediately thought of how destroying the Monarch Butterfly wintering grounds in Mexico would have the same impact on Monarchs.