Monarch butterfly life cycle

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.

Transcript

Egg

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

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

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

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

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