Head
Antennae, eyes, palpi, proboscis
Antennae
From between the eyes emerge a pair of segmented antennae. These can be voluntarily angled at various positions, and are best thought of as a form of radar. They have many functions including pheromone detection, which is used for mate location and recognition.
Eyes
Butterflies and most other adult insects have a pair of spherical compound eyes, each comprising of up to 17000 " ommatidia "- individual light receptors with their own microscopic lenses. These work in unison to produce a mosaic view of the scene around them.
Palpi
Protruding from the front of the head are a pair of small projections called labial palpi, which are covered in olfactory( scent detecting) sensors. Similar sensors are also located on the antennae, thorax, abdomen and legs.
Proboscis
The proboscis consists of a pair of interlocking C-section channels that when linked together form a tube, much like a drinking straw. This tube can be coiled up like a spring for storage, or extended to enable the butterfly to reach deep into flowers to suck up nectar. If the proboscis gets clogged with sticky fluids the 2 sections can be uncoupled and cleaned.
Thorax- legs & abdomen
Thorax
The thorax consists of 3 body segments which are fused together, forming a chitinous cage which contains the flight muscles, and acts as an anchor point for the legs.
Legs
All adult butterflies have 3 pairs of legs, except in the Nymphalidae and in males of certain other groups, where the front pair are reduced to brush-like stumps and modified as chemoreceptors.
Abdomen
The abdomen contains the digestive system, breathing apparatus, a long tubular heart. The abdominal exoskeleton is multi-segmented. Each of the 10 segments is comprised of a ring of a hard material called chitin. The segments are linked by flexible tissues, allowing the abdomen to bend, a necessity for copulation and egg-laying.
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