I remember reading a short kids sci-fi story when i was younger. I think it was a book but it might have been something else.
In this book a fleet of aliens make first contact with earth and as soon as they meet in person the humans start compulsively slurping up the aliens. Then people start getting weird symptoms until finally another fleet of aliens show up and also get eaten, which leads to the aliens fusing into their final form and flying back out of people, then explaining it was part of their reproductive cycle.
I just kinda remembered it this morning but i can't remember what it's called, can anyone help?