Insect Antennae and Mouthparts Quiz

Insect Antenna

• Antennae are extremely varied in shape and number of segments, and are important diagnostic features.
• Typical insect antenna consists of three basic segments: scape (base), pedicel (stem), and flagellum (often comprising many units known as flagellomeres).
• The pedicel (second segment) contains the Johnston's organ, a collection of sensory cells.
• The number of flagellomeres can vary greatly and is often of diagnostic importance.

Types of Antennae

• Aristate antennae: pouch-like with a lateral bristle (e.g., house flies).
• Clavate antennae: gradually clubbed at the end (e.g., butterflies).
• Capitate antennae: abruptly clubbed at the end (e.g., carrion beetles).
• Filiformis antennae: thread-like shape (e.g., ground beetles).
• Geniculate antennae: hinged or bent like an elbow (e.g., bees and ants).
• Monoliform antennae: bead-like in shape (e.g., termites).
• Pectinate antennae: comb-like shape (e.g., fire-coloured beetles).
• Plumose antennae: brush or feather-like shape (e.g., moths and mosquitoes).
• Serrate antennae: sawtoothed shape (e.g., click beetles).
• Setaceous antennae: bristle-like shape (e.g., dragonflies).
• Lamellate antennae: segments at the tip are flattened and nested, resembling a folding fan.

Insect Head

• The insect head consists of the occiput, compound eyes, ocelli, frons, gena, clypeus, mandible, and labrum.

Insect Eyes

• Insects have 0-3 single-faceted organs called ocelli, usually between the antennae, which detect light intensity.
• Compound eyes are large, many-faceted structures called ommatidia on the upper side of the head capsule.
• Each ommatidium consists of a lens, transparent crystalline cone, light-sensitive visual cells, and pigment cells.

Insect Head - Antennae

• Insects have one pair of antennae, which may have the function of touch, smell, and in some cases, hearing.
• Antennae are used for navigation, food location, grasping (in some species), and detection of temperature, chemicals, and pheromones.

Insect Mouthparts

• Insect mouthparts have become variously modified to perform the function of ingestion.
• Mouthparts also indicate the food habits of the insect.
• The mouthparts of the mature adult insect may be different from those of its immature form.

Components of Insect Mouthparts

• Labrum (upper lip): a simple plate hinged to the exoskeleton of the head, containing chemosensory sensilla.
• Mandibles (true jaws): two compact, single-jointed, toothed appendages that work together sideways.
• Maxillae: two-segmented palp appendages that lie behind the mandibles and function as accessory jaws.
• Labium (2nd Maxilla): formed by the fusion of a pair of appendages serially homologous with the maxillae.