Butterflies mate then lay eggs on host plants. Host plants are plants that provide food for the caterpillars of a specific butterfly species. Butterfly eggs are extremely tiny (around 1 to 2mm, which is about the size of a pinhead) and easy to miss, but if you know what you are looking for you can spot them.
Spot a Female Butterfly Laying Eggs
Look for butterflies flying around your yard and garden. Use a guide book to determine the species and the host plants you have available for them. If you see a butterfly hovering around the leaf of a host plant for that particular species, chances are it is a female laying eggs. Go back after she has left to see whether there are eggs.
Eggs Adhere to Plants
When a female butterfly lays an egg (or eggs) on a host plant, she also secretes a sticky "glue" to hold the egg onto the plant. This glue will help protect the egg and keep it adhered to the plant. You should not try to remove butterfly eggs from a plant as that can destroy the eggs and the developing caterpillar.
Look for Butterfly Eggs on the Host Plants
Butterfly eggs can usually be found on the top or bottom of a leaf or a stem of the host plant. They are laid singly by the female butterfly or laid in small clusters of multiple eggs on the host plant. The clustered eggs may be laid in a distinct pattern or even on top of each other.
The Appearance of Butterfly Eggs Will Vary
The appearance of butterfly eggs will vary from species to species. They may be oval or circular, ribbed or smooth. Most butterfly eggs start out light-colored--yellow or white--then darken as the caterpillar develops and gets closer to hatching.
Hatching Butterfly Eggs
If you want to watch the eggs hatch and rear the caterpillars through their life cycle to become butterflies, you should cut the leaf or plant and put it into a safe container. Gently remove the leaf or section of the plant and place into a large jar, net butterfly habitat or lidded aquarium. The container should not be airtight as the eggs need air. Place the leaf or plant section on a wet paper towel inside the container. The wet paper towel will provide needed moisture without making the environment too wet.
Fascinating Part of Nature
It will take about one week for a caterpillar to emerge from its egg. After hatching, the caterpillar will eat the egg shell, then begin eating the host plant. Provide fresh leaves and stems from host plants for the caterpillars to feed on and enjoy watching this fascinating part of nature.