Youth Newsletter Archive

Life-cycle of a Butterfly: the Garden Acraea (Acraea horta)

Posted On: Saturday, April 1, 2023

Life-cycle of a Butterfly: the Garden Acraea (Acraea horta)

Every year I get so many phone calls and emails from people in a panic that their beautiful Wild Peach trees (Kiggelaria africana) are being stripped of their leaves by thousands of little spiky blue-black caterpillars.

These caterpillars are the babies of the beautiful orange Garden Acraea butterfly. I thought I would tell you more about the interesting life cycle of this butterfly.

The miracle of metamorphosis

Butterflies are insects, and like all insects, they go through a few changes from when they are babies to become the beautiful adult butterflies that we love to see fluttering around in our gardens. The process of these changes, where the egg and baby (larval) stage is completely different to the adult, is called metamorphosis. (Meta = many and morphe = form).

Butterfly eggs

The female Garden Acraea lays her eggs on the underside of the leaves of the Wild Peach Tree mainly but will also sometimes lay her eggs on leaves of plants in the Passion-flower family (Passifloraceae). 

These eggs are tiny, and have little ridges on their sides. As the minute baby caterpillars grow inside them, they turn from a pearly white to dark brown or purplish black. 

Hungry Caterpillars

After about 9 days the eggs hatch and the starving hungry baby caterpillars immediately start gobbling their own eggshells and then the leaves of the plant they were born on. 

These tiny little caterpillars grow very fast, and as they grow, they need to shed their skins that become too tight for them. This is called molting. They need to molt about 5 or 6 times to keep up with their growth. In warm summer weather they will usually skip the final molt before pupating.

As they grow, the Garden Acraea caterpillars become very spiky, and turn bluish-black. If you look at them with a magnifying glass they really are quite beautiful.

This fully grown caterpillar has reached maturity and is about to pupate. They will position themselves upside down and spin a silky attachment for themselves to the wall or rock before they go into their next phase of development.

Caterpillars are part of the Ecosystem

Nature’s perfect timing is just amazing! These juicy little caterpillars are feeding busily on the leaves of the Wild Peach Trees just when the Diedrik Cuckoos start thinking about finding a mate to breed.  

Cuckoos are one of the only bird species that can eat these caterpillars, as most other birds find them extremely nasty-tasting (unpalatable).  The Diedrik Cuckoos feed almost exclusively on these caterpillars, and part of the male Cuckoo’s success in being chosen as a mate by a female Cuckoo is determined by how many delicious, juicy caterpillars he can find to feed her.  

The caterpillars are stopped from becoming too plentiful by the Cuckoos, and they also keep the beautiful cuckoos alive and present in our gardens when there are enough caterpillars around to keep their tummies full. This balance in nature is what keeps our gardens healthy and thriving.

Not only the cuckoos benefit from the caterpillars – the soil under the trees does too. As the caterpillars munch their way through the leaves of the Wild Peach tree, they poop a lot! This frass (caterpillar poop) as well as the skins shed by the growing caterpillars and the pupa skin provide important nutrients for the soil, making it more nourishing for the trees as well as other plants growing in the area. 

One can see why it is so important to avoid using poisons and pesticides. If we kill caterpillars thinking that they are destroying our gardens, we will never have the birds that eat them or the nourishment that they provide for the soil.

Caterpillars put themselves in “sleeping bags” to sleep.

The Garden Acraea caterpillars stop growing and crawl off the trees they have been feeding on and into sheltered places to pupate (become a pupa). They attach themselves to a dry space – a wall or rock or nearby plant and hang upside down. One could be forgiven for thinking that they are dead, but a wonderful change is busy happening in their bodies. The whole caterpillar transforms into a pupa – which has the most beautiful and detailed markings. 

The pupa provides a protective covering for the caterpillar that is changing into a butterfly. This covering stops the larva from drying out, as well as from some damage. It’s like pulling a hard but cosy sleeping bag closed over its developing body.

The birth of a butterfly

After about two and a half weeks, a magnificent adult butterfly emerges from the pupa. The pupa splits down the top, and the butterfly un-crinkles its wings and waits for the blood to pump through them until they are fully stretched out. 

When it’s ready to fly away, the butterflies will readily sip nectar from many different flowers around the garden. They also fly around to find a mate, and once the female butterfly is ready to lay eggs, she uses her feet to “taste” the leaves of plants by gently stamping on them. This is how she knows that she is on the right kind of plant for the caterpillar babies to feed on.

When the eggs have been laid, the circle of life for these pretty butterflies is complete.

A classroom in your garden

If you are lucky enough to have a Wild Peach Tree in your garden, keep a look out for these butterflies and their caterpillars. They are sure to provide you with lots of fun watching them grow and complete their life cycle.

Growing lots of flowers that produce nectar will provide food for all kinds of adult butterflies in your garden. 

Butterflies also need places to warm up on cold mornings, so provide wood and stone in warm sunny areas is a good idea. Many butterflies also love sucking up minerals from mud and so a muddy patch is also recommended. It does not have to be big or deep, just shallow and in a sunny spot.

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