Ladybugs go by several other names: lady beetles, ladybug beetles, and ladybird beetles. Regardless of what you call them, these beetles belong to the family Coccinellidae. All ladybugs progress through a four-stage life cycle known as complete metamorphosis.
Egg – Embryonic Stage:
Once she has mated, the female ladybug will lay a cluster of 10-50 eggs on a plant with suitable prey for her offspring to eat when they hatch. Usually, she'll choose a plant infested with aphids. Between spring and early summer, a single female ladybug may produce up to 1,000 eggs.
Scientists believe ladybugs lay both fertile and infertile eggs in the cluster. When aphids are in limited supply, the newly hatched larvae will feed on the infertile eggs.
Larvae typically emerge from their eggs in about 4 days, although species and environmental variables such as temperature may shorten or lengthen this time frame.
Larva – Larval Stage:
Ladybug larvae look somewhat like tiny alligators, with elongate bodies and bumpy exoskeletons. In many species, the ladybug larvae are black with brightly colored spots or bands.
In the larval stage, ladybugs feed voraciously. A single larva can consume dozens of aphids per day. Larvae feed on other soft-bodied plant pests as well, including scale insects, adelgids, mites, and insect eggs. Ladybug larvae don't discriminate when feeding, and will sometimes eat ladybug eggs, too.
The newly hatched larva is in its first instar. It feeds until it grows too big for its cuticle, at which time it will molt. After molting, the larva is in the second instar. Ladybug larvae usually molt through four instars, or larval stages, before preparing to pupate. The larva will attach itself to a leaf or other surface when it is ready to pupate.
Pupa – Pupal Stage:
In its pupal stage, the ladybug is usually yellow or orange with black markings. The pupa remains still, attached to a leaf, throughout this stage. The ladybug's body undergoes a remarkable transformation, directed by special cells called histoblasts. The histoblasts control a biochemical process through which the larval body is broken down and reformed into the adult ladybug.
Depending on the species and environmental variables such as temperature, the pupal stage may last 3 to 12 days.
Adult – Imaginal Stage:
Newly emerged adults, or imagos, have soft exoskeletons, making them vulnerable to predators until their cuticles harden. They also appear pale and yellow when they first emerge, but soon develop the deep, bright colors for which ladybugs are known.
Adult ladybugs feed on soft-bodied insects, just as their larvae do. Adults overwinter, usually hibernating in aggregations. They mate soon after becoming active again in the spring.