Why does the butterflies lay eggs on leaves of plants?
答案：
Egg is the first stage of the life cycle. Most butterfly caterpillars eat only one or a few species of plants. Some butterflies lay their eggs on the undersides of leaves, to avoid direct sunlight and drying of the eggs, and can avoid rainwater washing away the eggs.
资料来源：
Brainly【Why does butterfly lay their eggs on the leaves of plants】
This way, when the eggs hatch into tiny caterpillars (larvae), their food is all around them and the can start eating immediately.
https://www.enchantedlearning.com/subjects/butterfly/lifecycle/Adult.shtml
