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  • The life cycle of the monarch butterfly. Click on one of titles to find out more about each stage.

    Click on the stages tabs to learn more about the different stages of the life cycle of the monarch butterfly.

    Acknowledgements: Background plate images of life cycle stages courtesy of Jacqui Knight and Kath Widdowson.



    Egg – location

    Female monarch butterflies lay tiny creamy-yellow eggs generally on the underside of a milkweed leaf.

    Image: Keith Moore

    Egg – time

    Eclosion (hatching) occurs in 4–8 days, depending on the temperature.

    Image: Jacqui Knight

    Egg – development

    As the larva develops, the egg changes in colour. The egg is grey when it’s about to hatch and the black head is visible. If you use a magnifying glass, you can see it moving around.


    Larva – head or tail?

    Soft, black filaments are at either end. The filaments behind the head wiggle when the larva feeds. Note that the filaments are not antennae. Three pairs of true legs are near the head. Each leg has a single claw. Prolegs are at the back. These help the larva cling to the plant.

    Image: Jacqui Knight

    Larva – exoskeleton

    As the larva grows, it has to moult (shed) its exoskeleton (skin). A monarch larva moults 5 times. The stage between moults is called an instar.

    Image: Jacqui Knight

    Larva – an eating machine

    The larva emerges to become an eating machine. In 2–3 weeks, it grows to about 2,700 times its birth weight. If a human baby grew in a similar manner, it would weigh 8 tonnes when 2 weeks old!

    Image: Jacqui Knight


    Pre-pupa – silk mat

    The larva’s 5th and final moult comes when it weighs about 1.5g and is about 55mm long. The larva finds a sheltered site and produces a tightly woven silk mat. It hooks its rear prolegs into the silk and hangs downwards.

    Image: Jacqui Knight

    Pre-pupa – final moult

    Hormones kick in, and within 2 days, the larva moults into a pupa.

    Image: Jacqui Knight


    Pupa – chrysalis

    Chrysalis is a Greek word for gold. Scientists are unsure about why the gold band and spots appear on the chrysalis.

    Image: Jacqui Knight

    Pupa – bodily changes

    While in the pupal stage, the larval tissue reassembles itself. The straw-like proboscis replaces jaws. Wings and reproductive organs develop.

    Image: Cosima Ray

    Pupa – time

    After about 10 days, the final moult reveals an adult butterfly. The enlarged abdomen is full of fluid. The butterfly pumps the fluid into its crumpled wings until they become full and stiff.

    Image: Jacqui Knight


    Adult butterfly – size

    Adult butterflies do not continue to grow but remain the same size for life.

    Image: Kath Widdowson

    Adult – antennae

    The antennae detect pheromones – odour chemicals – used in courtship.

    Image: Cosima Ray

    Adult – feet

    Butterflies use their feet to locate and taste nectar.

    Image: Cosima Ray

    Adult butterfly – sex

    Male butterflies have two spots on the hindwings. Females have thicker black webbing within the wings. Females lay between 300–400 eggs at a rate of up to 40 per day.

    Images: Darren Gedye

    Rights: University of Waikato Published 16 May 2010, Updated 18 August 2017 Size: 410 KB Referencing Hub media
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