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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