The Halakha regarding locusts, and all kosher animals for that matter, is that one is allowed to eat a specific type of animal only if there is a "continuous tradition" that affirms that it is kosher. It is not enough that the locust seems to conform to the criteria mentioned in the Torah. This does not mean that one must possess a 'personal tradition' in order to eat locusts. If one travels to a place where the people do have a tradition, the new arrival would also be allowed to eat them. The Yemenite Jews and some others had such a continuous tradition.