Papilio demodocus, also known as the citrus swallowtail, is a large swallowtail butterfly

Swallowtail butterfly

Swallowtail butterflies are large, colorful butterflies that form the family Papilionidae. There are over 550 species, and though the majority are tropical, members of the family are found on all continents except Antarctica...

 common to sub-Saharan Africa

Sub-Saharan Africa

Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

. It is a pest species, the caterpillar

Caterpillar

Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...

 feeding on citrus trees.

Life cycle

Citrus swallowtails pass through approximately three generations per year. Eggs are laid singly on citrus tree leaves.

Eggs

Female butterflies lay their eggs singly on citrus leaves. After about six days, the egg hatches into an immature larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

.

Immature larva

The immature larvae are black, yellow, and white with spikes. Their coloration provides effective camouflage

Camouflage

Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

, as they resemble bird droppings. They grow to a length of 10 or 15 mm before changing into mature larvae.

Mature larva

Mature larvae are green with white or pink markings and eyespots. They grow to a maximum length of about 45 mm.

Mature caterpillars lack the camouflage of their immature state. Instead, when threatened by a bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

 or other predator, they produce a forked, orange-coloured organ known as an osmeterium

Osmeterium

The osmeterium is a fleshy organ found in the prothoracic segment of larvae of Swallowtail butterflies including Birdwings. This organ emits smelly compounds believed to be pheromones. Normally hidden, this forked structure can be everted when the caterpillar is threatened, and used to emit a...

. The organ emits a strong smell which acts as a discouragement to the predator.

Pupa

The caterpillars attach themselves to branches with silk

Silk

Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...

, transforming into pupa

Pupa

A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...

e. They remain in the pupal form for 2–3 weeks before emerging as adults.

Adult

Adult butterflies have black and yellow markings with red and blue eyespots. Female butterflies tend to be larger than males.

Natural enemies

Citrus swallowtail eggs and pupae are known to be parasitised

Parasitoid

A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...

 by certain species of parasitic wasp

Parasitic wasp

The term parasitoid wasp refers to a large evolutionary grade of hymenopteran superfamilies, mainly in the Apocrita. They are primarily parasitoids of other animals, mostly other arthropods...

, notably Ooencyrtus (eggs) and Pteromalus puparum (pupae).