Q.What Wild Animal Eats Ornamental Poppy Leaves
Transplant disappeared. Regrow from root. Disappeared again. Never grew big. Leaves disappeared too early
Certified GKH Gardening Expert
Many, from insects, to rabbits, to birds and anything in between can eat young seedlings of all sorts.
It would be very hard to say, exactly, what ate your seedlings without seeing signs, unfortunately.
Here are some articles that will help you with many different types of pest control:
https://www.gardeningknowhow.com/special/organic/what-are-organic-pesticides.htm
https://www.gardeningknowhow.com/category/plant-problems/pests/animals