Structure and the Life Processes of Butterfly


This  blog post provides readers with the following objectives. The reader will be able to:
o   Identify Butterfly.
o   Discuss the life cycle and other life processes of the Butterfly.
o   Describe the external features of the larva (caterpillar), pupa and adult butterfly



Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera

Most species are diurnal (mainly day-flying insect). Butterflies feed on nectar of flower.

Structure of Butterfly

Diagram of butterfly with labels

The body is divided into three segments: the headthorax, and the abdomen.

The head bears a pair of compound eyes, a mouthparts and a pair of prominent antennae with knob at the tip.

The mouthparts is modified into long tube called proboscis, which is used for sucking nectar. The proboscis is formed from a pair of maxillae. It is coiled up when not in used. The head is covered by hair-like scales.  

The thorax consists of three segments; prothorax, metathorax and mesothorax, each bearing a pair of jointed walking legs. The thorax is hairy. 

The mesothorax and metathorax bear a pair of membranous wings each. The wings are clothed with scales often of bright colors. Scales also cover the head, parts of the thorax and abdomen as well as parts of the genitalia.

The abdomen is composed of ten segments. The anus is situated on the last segment.

Head of the citrus swallowtail butterfly

Life Cycle of  Butterfly

Reproduction (complete metamorphosis of life cycle) of Butterfly

The life cycle of butterfly shows complete metamorphosis: egg; larva or caterpillar; pupa or chrysalis; and imago or adult.


Butterfly is oviparous or egg-layers. After mating eggs are laid either singly or in small groups on the undersurface of food plants; cabbages and young citrus leaves.

The egg is spherical, whitish, pale green in color and with almost smooth outer shell.T he eggs hatch in few weeks, into larvae called caterpillar.



It has three distinct body parts: the head, the thorax and the abdomen. The head has a pair of short antennae, mouthparts, and six pairs of simple eyes called ocelli.

Each of the three thoracic segment bears a pair of jointed true legs which ends with claw.

The abdomen is composed of ten segments. The 3rd to 6th abdominal segments bear a pair of false legs called prolegs. The prolegs have tiny hooks known as crochets that hold the larva onto its silk mat or leaf. Clasper is borne on the last segment.

Some caterpillars have the ability to inflate parts of their head to appear snake-like. They have false eye-spots to enhance this effect. Some caterpillars have special structures called osmeteria (singular: osmeterium) which emit foul smelling chemicals. These are used in defense.

Caterpillars are ‘eating machines. They actively feed plant leaves and spend practically their time in search of food. Caterpillars undergo ecdysis and develop through four stages or instars before changing into pupa or chrysalis.

larva of butterfly (caterpillar)


The pupa is a resting stage where all the tissues in the caterpillar's body are rearranged.

The caterpillar stops feeding and attach itself to a stem or leaf. It secretes a silk pad called a cremaster on the twig and attaches its claspers to it.

It is held in upright position by secreting silk girdle around the thorax.

The chrysalis usually moves the abdominal segments rapidly or produce sounds to scare potential predators.

The internal structures of the caterpillar break down and re-organized into adult organs. The chrysalis becomes almost transparent when the butterfly is about to emerge.

The pupal stage lasts for about 11 days.

developing stages in the life cycle of the citrus swallowtail butterfly


The adult, sexually mature stage of the insect is known as the imago. When an adult emerges from the split chrysalis, it hangs upside down and pumps blood into its delicate wings and waits for them to dry. It can fly a few hours after emerging.

Citrus swallowtail butterfly - side view of resting position

Difference between Butterfly and Moth



It is a diurnal insect

It is a nocturnal insect

It has antenna with knob at the tip

The tip of the antenna is pointed

It has brightly scales on its body

It is dull colored

The wings are separated and not joined

The wings are connected to each other

When at rest the wings are folded vertically

The wings are spread horizontally at rest

Economic Importance of butterfly

1. Caterpillars cause much damage by eating leaves of food crops.

2.  Some caterpillars are used in industry. Caterpillars such as silk-worm produce quality silk which is used for making silk fabrics and clothes.

3.  Some caterpillars are roasted and eaten as meal in certain places.

4.   Some butterflies are agents of pollination of some plants.

5.  Beautiful colored butterflies are mostly used as ornamental. 

6.  Caterpillars of a few butterflies (e.g., Harvesters) eat harmful insects.


Control of Caterpillar of Butterfly

1.     Caterpillars can be control through the use of pesticides, biological control and agronomic practices.
2.  By incorporating host plant resistance (HPR) through plant breeding. This is another approach used in reducing the impact of caterpillars on crop plants.

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