Monarch Butterfly (Danaus plexippus)
The life of a monarch begins when a female adult monarch lays an egg, usually on the underside of a milkweed leaf. The egg hatches after 3-5 days to reveal a very small larva (caterpillar).
Over a period of 9-15 days, the larva eats milkweed, grows and molts (i.e., sheds its skin) five times as it rapidly increases in size – it actually increases its body mass about 2,000 times! The period between each molt is called an instar and monarch larvae undergo five instars.
When the larva has finished eating milkweed, it pupates and spends another 9-14 days as a chrysalis (or pupa) undergoing a complete metamorphosis. Once fully developed, a delicate adult butterfly emerges from the pupa, hanging from its pupal casing while it pumps fluid from its abdomen into its wings. In a short time, the wings dry and harden, and the new monarch flies off to find nectar and to mate. If it is a female, it looks for milkweed and begins laying eggs.
A new cycle. A new generation
The eggs laid by the female monarch start the cycle over again - hatching, growing, pupating, emerging, mating, laying eggs - living up to 6 weeks. Depending on location, there can be three to four generations throughout the summer.
The monarch's life cycle is only part of its fascinating story - how this tropical species survives winter is even more captivating! Check out the monarch's annual cycle to learn more.
Monarch Biology and Conservation
For a deeper dive into monarch biology and the issues impacting monarch populations, click below to watch a video on monarch butterfly biology and conservation. Dr. Karen Oberhauser, MBF board member and monarch expert, takes you through the monarch's life cycle, habitat needs, and migration patterns, as well as the environmental threats faced by monarchs and conservation measures being taken to support their survival. Video is approximately 51 mins.