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Questions and Answers
What is the term for the dorsal body plate of each thoracic segment?
What is the term for the dorsal body plate of each thoracic segment?
What is the name of the segmental plate that makes up the thoracic sternum?
What is the name of the segmental plate that makes up the thoracic sternum?
What is the function of the thorax in insects?
What is the function of the thorax in insects?
How many pairs of spiracles are found in the pterothoracic region?
How many pairs of spiracles are found in the pterothoracic region?
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What is the name of the basal segment of an insect leg?
What is the name of the basal segment of an insect leg?
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What is the term for the lateral body wall of the thorax?
What is the term for the lateral body wall of the thorax?
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What is the main function of the tibia in an insect's leg?
What is the main function of the tibia in an insect's leg?
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Which type of leg is characterized by a fused trochanter with femur and powerful muscles for jumping?
Which type of leg is characterized by a fused trochanter with femur and powerful muscles for jumping?
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What is the main function of the pretarsus in an insect's leg?
What is the main function of the pretarsus in an insect's leg?
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Which of the following insects has a cursorial leg modification?
Which of the following insects has a cursorial leg modification?
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What is the main function of the raptorial leg in an insect?
What is the main function of the raptorial leg in an insect?
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Which segment of the insect leg is usually larger and is known as Basitarsus?
Which segment of the insect leg is usually larger and is known as Basitarsus?
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What is the primary function of tegmina in insects?
What is the primary function of tegmina in insects?
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Which type of insect wing is characterized by a clubbed free end, a slender stalk, and an enlarged base?
Which type of insect wing is characterized by a clubbed free end, a slender stalk, and an enlarged base?
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What is the term for the wing coupling apparatus found in higher pterygotes?
What is the term for the wing coupling apparatus found in higher pterygotes?
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Which type of insect wing is characterized by a fringe of elongate setae?
Which type of insect wing is characterized by a fringe of elongate setae?
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What is the primary function of scales on the wings of butterflies and moths?
What is the primary function of scales on the wings of butterflies and moths?
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In which group of insects do the wings move independently?
In which group of insects do the wings move independently?
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What is the primary function of the tarsus in the natatorial leg of water beetles?
What is the primary function of the tarsus in the natatorial leg of water beetles?
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Which type of leg is characterized by a stout tibia with a thumb-like process at one end?
Which type of leg is characterized by a stout tibia with a thumb-like process at one end?
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What is the primary function of the pulvilli in the sticking leg of a house fly?
What is the primary function of the pulvilli in the sticking leg of a house fly?
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Which type of leg is characterized by a basket-like structure used for capturing prey in flight?
Which type of leg is characterized by a basket-like structure used for capturing prey in flight?
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What is the primary function of the tibial tines in the burrowing leg of a mole cricket?
What is the primary function of the tibial tines in the burrowing leg of a mole cricket?
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Which type of leg is characterized by a clasping mechanism used for mating?
Which type of leg is characterized by a clasping mechanism used for mating?
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What is the characteristic feature of the amplexiform type of wing coupling?
What is the characteristic feature of the amplexiform type of wing coupling?
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Which type of wing coupling is found in male fruit sucking moths?
Which type of wing coupling is found in male fruit sucking moths?
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What is the term for the hook-like bristle on the fore wing of male fruit sucking moths?
What is the term for the hook-like bristle on the fore wing of male fruit sucking moths?
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In which type of wing coupling does the jugal lobe of the fore wing lie beneath the costal margin of the hind wing?
In which type of wing coupling does the jugal lobe of the fore wing lie beneath the costal margin of the hind wing?
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What is the term for the group of stout bristles on the costal margin of the hind wing of female fruit sucking moths?
What is the term for the group of stout bristles on the costal margin of the hind wing of female fruit sucking moths?
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Study Notes
Insect Legs and Their Types
- Insect legs are modified for various functions, such as walking, running, jumping, grasping, and digging
- Segments of a leg:
- Coxa: basal segment, freely movable
- Trochanter: small second segment, usually one-segmented, but two-segmented in dragonflies and damselflies
- Femur: largest and stoutest part of the leg
- Tibia: long, provided with many spines, helps in footing
- Tarsus: subdivided into many tarsomeres (1 to 5), basal segment is usually larger and is known as basitarsus
- Pretarsus: structures beyond the tarsus, including two claws, a median pad (arolium), and two basal pads (pulvilli)
Leg Modifications
- Ambulatorial (Walking) legs:
- Foreleg and middle leg of grasshopper
- Femur and tibia are long
- Cursorial (Running) legs:
- Cockroach
- Elongate, slimmer legs
- Femur is not swollen
- Saltatorial (Jumping) legs:
- Hind legs of grasshopper
- Can hop (jump, leap, saltate, vault)
- Trochanter fused with femur
- Femur enlarged and accommodated with powerful muscles
- Tibia – long and slender with two rows of spines
- Raptorial (Grasping) legs:
- Forelegs of preying mantids, giant water bug
- Hold or grasp their prey in between the leg
- Coxa is elongate and outstretched
- Femur and tibia spiny, grooved, work against each other to grasp prey
- Fossorial (Digging/Burrowing) legs:
- Mole cricket
- Forelegs burrow or rake through the soil to dislodge soil particles
- Tibia is rake-like, and femur is stout
- Tibia has 2-3 strongly pointed tines at the distal part
- Tarsus has tines like the basitarsus, which works against the tibial tines to shear rootlets
Other Leg Modifications
- Natatorial (Swimming) legs:
- Hind legs of water beetles and water bugs
- Segments are much flattened
- Femur, tibia, and first four tarsomeres are broader and flattened with rows of strong setae (hairs) adapted for rowing
- Scansorial (Clinging) legs:
- Head louse
- Tibia is stout, bearing a thumb-like process at one end
- Tarsus is unsegmented with a single claw
- Tarsal claw fits against the tibial thumb while clinging to the hairs
- Sticking legs:
- All three pairs of legs of the housefly
- Pretarsus has a pair of lateral adhesive pads (pulvilli)
- Median spine is the empodium
- Pulvilli have dense mats of tiny glandular hairs (tenent hairs)
- Smooth surface and roof allow for walking in an upside-down position
- Basket-like legs:
- Legs of dragonflies and damselflies
- Legs are just behind the head and anterior in position
- Spiny and closely placed
- Seize prey in flight and carry captured insects in a basket
- Clasping legs:
- Forelegs of male water beetles
- Tarsus is flattened with adhesive discs
- Clasp the mate during copulation
Insect Wings and Their Types
- Wing modifications:
- Tegmina (Tegmen): e.g., the forewings of cockroaches, grasshoppers
- Leathery wings that protect the membranous hind wings
- Elytra: e.g., the forewings of beetles, weevils
- Heavily sclerotized and horny wings that protect the membranous hind wings
- Hemelytra: e.g., the forewings of heteropteran bugs
- Wings are more sclerotized basally, but the distal half remains membranous
- Haltere: e.g., the hind wings of true flies, mosquitoes, male scale insects
- Wings are modified into a vibrating, sensory appendage
- Fringed wings: e.g., the wings of thrips
- Wings are very narrow with a fringe of elongate setae
- Scaly wings: e.g., the wings of butterflies, moths
- Wings are clothed with scales
- Scales are flattened, unicellular modified setae
- Tegmina (Tegmen): e.g., the forewings of cockroaches, grasshoppers
Wing Coupling
- In primitive winged insects (pterygotes) and in Odonata (dragonflies) and Isoptera (termites), the wings move independently
- In higher pterygotes, the wings of a side operate in union by a wing coupling apparatus
- Types of wing coupling:
- Hamulate: e.g., honey bees
- A series of hooks or hamuli (small hooks)
- Frenate: e.g., fruit-sucking moths
- A stout bristle (frenulum) arising from the costal margin of the hind wing interlocks with a hook-like bristle (retinaculum) on the subcostal vein of the forewing
- Amplexiform: e.g., butterflies
- The forewing and hind wing of either side get coupled by simply overlapping each other
- Jugate: e.g., Hepialidae
- The jugal lobe of the forewing lies beneath the costal margin of the hind wing, so that the latter is held between the jugum and the rest of the forewing
- Hamulate: e.g., honey bees
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Description
Test your knowledge of the insect thorax, including its segments, body plates, and appendages. Learn about the prothorax, mesothorax, and metathorax, and how they contribute to the insect's body structure. Explore the different types of body plates and their functions.
