Butterflies laying their eggs on milkweed plants occurs at the community level of the biosphere hierarchy.
The biosphere may be defined as the area of the planet where organisms live, including the ground and most commonly air.
During the process of pollination, butterflies lay their eggs on the milkweed plant, which is considered under the community level of the biosphere hierarchy.
Therefore, Butterflies laying their eggs on milkweed plants occurs at the community level of the biosphere hierarchy.
To learn more about Biosphere hierarchy, refer to the link;
https://brainly.com/question/765755