From the USPS website
9.3.3 Small Cold-Blooded Animals
Small, harmless, cold-blooded animals (except snakes and turtles) that do not require food or water or attention during handling in the mail and that do not create sanitary problems or obnoxious odors are mailable (e.g., baby alligators and caimans not more than 20 inches long, bloodworms, earthworms, mealworms, salamanders, leeches, lizards, snails, and tadpoles).
Remember no caimans :lol: