I got the mailing tube, recognized the return address, and blithely went to cut it open with a box cutter. An insect larva fell out. "That's odd", I thought, "but, it came from an area well known to have plenty of insect life. Must have wandered in." I scooped it up and tossed it outside. Then I went to dispense my plastic, and another handful of larvæ fell out, and commenced to crawling around the floor. Wait, what? Why are all these live grubs in here? I didn't expect this! What's going on? Also, eew! I put the mailing tube in the garbage can, managed to gather up all the squirming grubs, and dumped them in the can too. I could hear them squinkling* around in the plastic liner, *shudder*.
What's going on here? What are these? Why are they here? Where's my plastic?
I went and called the person who sent the package, who expressed utter bafflement. She hadn't sent anybody any larvæ, the package sounded like the one she sent. The plastic should be in there.
So I reluctantly went outside, retrieved the package from the garbage can, and timidly went through it. There were a lot of larvæ. So many larvæ! Here, have a picture:
Bears an unsettling resemblance to the brain-damaging eels of Ceti Alpha IV, doesn't it? However, I did fine one additional thing:
A form, apparently from the Dulles Mail Sorting Facility. Crumpled up to fit in the mailing tube, but not carrying any additional information.
So what are these beasties? They don't have legs of any kind, which means they're probably fly (Diptera) larvæ, so maggots of some sort. Yay. Some research on my part reveals that they're very likely Hermetia illucens, or black soldier fly larvæ. Hmm, these are used to digest compost, repel houseflies, and feed chicken and fish. They're good guys, harmless, and conceivably something somebody would send in the mail.
My best guess is that a shipment of these things broke open, and got into other containers, and when my package arrived at Dulles, triggered some sort of "live creatures" alert, and they opened the package to investigate. Finding innocuous larvæ, stuffed an inspection form in, and sent it on its way, discarding the plastic in the process. I don't know.