If you haven’t raised butterflies from eggs, you have some fun waiting ahead for you!
Eggs come in many colors, shapes, and sizes. Butterflies and moths lay eggs in sizes from microscopic to almost the size of a BB.
If you catch a wild female butterfly and place her in a container for a few hours to collect a few eggs, she has probably already paired. Her eggs should be fertile. After she lays a few eggs, you can release her back outside to continue laying eggs in nature.
A close examination of host plants may reveal eggs in the wild. Learning which butterfly uses which plant as a host plant will greatly increase your chances of finding eggs in your yard or on a trek in nature. Some butterflies, like Viceroy butterflies, lay eggs only on the tip of a leaf. Others, like Julia butterflies, prefer to lay their eggs off but close to their host plants. Some butterflies, like Pipevine Swallowtails, often lay eggs in clusters. Others lay eggs in towers. Still others lay eggs singly.
Infertile eggs will collapse upon themselves. Roundish eggs will collapse downward. Tall eggs will collapse inward.
Trichogramma wasps may have laid eggs in a butterfly or moth egg and you may have trichogramma wasps emerge instead of a butterfly or moth caterpillar.
If you find eggs, you can place them in a small sealed cup and wait for the eggs to hatch. Hatchling caterpillars are super tiny. Remember, they had to fit inside the egg! If moisture condenses on the inside of the cup, add a few holes in the lid, cover the top with a coffee filter, and replace the lid. This provides a barrier to block the caterpillars from crawling out of the cup yet also provides ventilation for extra humidity to escape.
Hatchling caterpillars need food NOW. They are too small to survive long without food. You can add a tiny snippet of food to the cup daily. Always place the piece of leaf on the brightest side of the cup. Some species have an instinct to go to light that is so strong that they will sit on the bright side of the cup and starve to death.
Another method to hatch eggs is to place the pieces of leaves with eggs in small piece of coffee filter, paper towel, or similar item. Attach the filter with eggs to the living plant with a paper clip or twist tie. When the caterpillars hatch, they will crawl to the living leaves on the plant.