Butterflies of the World - Lifecycle, Ecology, Taxonomy, Conservation, Photography, Butterfly Holidays, Photo Galleries, Book Reviews and more.........
Text and photographs protected by Copyright © Adrian Hoskins 2007, and must not be published in part or in whole elsewhere without prior written permission from the author.
The butterfly lifecycle

The Lepidoptera ( butterflies, skippers and moths ), belong to a group of insects called Endopterygotes, all of which go through 4 distinct phases in their lifecycles :

Section 1 - EGG                ( ovum / ova )
Section 2 - CATERPILLAR   ( larva / larvae )
Section 3 - CHRYSALIS      ( pupa / pupae )
Section 4 - ADULT             ( imago ) 
 
 

When a caterpillar becomes full grown, it undertakes a final moult. At this time it usually anchors itself by it's tail to a pad of silk, and in the case of Swallowtails ( Papilionidae ), Whites ( Pieridae ) and Metalmarks ( Riodinidae ), it spins a silken girdle around it's waist to secure it to a twig or leaf.

It hangs motionless for a day or two, preparing itself for the moult, and during this time the prolegs start to shrink, the thoracic segments become enlarged, and the larva adopts a curled position. This stage in the lifecycle, just prior to pupation, is often referred to as the "pre-pupa".
Gonepteryx rhamni, fully grown larva ( pre-pupa ) just prior to the final moult

When the final moult takes place, the skin splits behind the head, but instead of a caterpillar walking out of the old skin, what emerges is quite different in nature - a legless, wriggling, non-eating entity called a pupa or chrysalis.

At first the pupa is soft, limp, and very vulnerable to attack by parasitoid wasps and flies, but within a few hours the skin forms into a hard outer shell that will protect the insect until it eventually emerges as an adult butterfly.
Gonepteryx rhamni, pupa suspended from buckthorn leaf

Anatomy

Eggs and caterpillars are asexual, but pupae can be distinguished as male or female. A male pupa will have 2 tiny bumps close to it's tail, corresponding with the anal claspers of the adult butterfly. It is also usually slimmer and lighter than a female pupa. Other details of the adult butterfly can be seen on the pupa - antennae, legs, eyes, wing cases and palpi. When newly formed, pupae are soft and vulnerable to attack by parasitoid wasps, but they quickly harden.

Cocoons

Most butterfly pupae hang unprotected from leaves or twigs, and rely on camouflage as their only means of defence. Many moth pupae however ( Saturniidae, Lasiocampidae, Zygaenidae, Notodontidae etc ) are formed within a tough silken cocoon. This protects them from extremes of weather, and from attack by carnivorous insects.

Skipper butterflies ( Hesperiidae ) also pupate within cocoons, but in this case they are much more flimsy affairs - little more than a "nest" made by spinning together a few leaves with strands of silk.

Polyommatine butterflies ( Blues ), some Satyrines ( Browns ), and many moth families
( Sphingidae, Geometridae, Noctuidae etc ) pupate without a cocoon, on or just below the surface of the ground. These pupae, particularly those of the Polyommatinae, tend to disseminate pheromones which act as chemical messages to deter attack by ants.

Diapause

The pupal stage of the lifecycle can last anything from 1 to 40 weeks depending on the species. In polyvoltine species ( those which have more than one generation per year ), the summer pupal stage will be short - often less than a week; but the winter pupal stage may last several months.

Metamorphosis

The popular belief that the bodily fluids within the pupa break down into a "soup" and later reform in the shape of a butterfly is largely untrue. The change from larva to adult butterfly is actually a very gradual process. Clusters of stem cells from which the wings develop are present in segments 2 and 3 of small larvae. They replicate and diversify during larval development. In the last few days prior to pupation the development accelerates, so that the wings are almost fully formed at the time of pupation. The same applies to the antennae, eyes and palpi, all of which are visible on the newly formed pupa.

Within the pupa the changes that take place are surprisingly minor. The wing scales develop as plate-like extensions from cells on the wing surface. The heart, brain, eyes, antennae and proboscis all develop from the fairly simple organs "hidden" within the larva, into the recognisable features of an adult butterfly.
Gonepteryx rhamni, pupa with wing patterns showing through, just prior to emergence

NEXT >> ( adult butterflies and moths )

 
Related subjects :
 
Anatomy - the structure and biology of adult butterflies.
Parasitoids and Predators - of eggs, larvae, pupae and adult butterflies.
 
Courtship rituals and many other aspects of adult behaviour are discussed in detail in the individual species accounts, which can be accessed from the Species Index, or by clicking on thumbnail images of butterflies in the Photo Galleries.
 
Text and photographs protected by Copyright © Adrian Hoskins 2007-2008, and must not be reproduced or published in part or in whole elsewhere in any form without written permission from Adrian Hoskins. Breach of copyright will be pursued by litigation.
 
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