I would recommend actually putting them in your Check-in luggage and declaring them to the USDA agents at the airport. I suspect they probably put outgoing packages through an agricultural check (like they do at the airports) and it’s much easier to explain your specimens in person. The agents stationed there told me they were mainly looking out for O. Rhinoceros and invasive Gastropods like the GALS, and let me bring (to America) a species of invasive (though not pest status) flower beetle and another invasive roach species