Here is a Zebra Longwing Butterfly (Heliconius charitonius) laying an egg on a Passiflora vine. It was shot at the temporary butterfly exhibit at the Ohio State Fair. You can see on the leaf above an to the left of her abdomen an egg which has recently hatched. The Fair doesn't have the same constraints as many butterfly exhibits because they only need it to look good for two weeks. Most places don't have host plants for females to lay eggs on since the caterpillars would eat them!