Insect Anatomy

Question 1

Insect Tagmata

Answer 1

head, thorax, abdomen

Question 2

head
- overall name
- parts of head

Answer 2

prosoma

• mouthparts
• antennae
• compound eyes
• ocelli

Question 3

thorax

Answer 3

mesosoma

Question 4

abdomen

Answer 4

metasoma

Question 5

What are mouthparts?
What are they used for?
What are the parts of the mouthparts?

Answer 5

modified, paired feeding appendages

used to capture + manipulate food

Labrum, Mandible x2, Maxilla x2, Labium

Question 6

What is the Labrum? and whats its function?

Answer 6

plate (sclerite) serves as upper lip in insects w/ chewing mouthparts

helps to pull food into the mouth

Question 7

What are the mandibles? function? movement?

Answer 7

paired appendages of 4th body segment become 1st pair of mouthparts

used to chew, cut/tear food, carry things, fight, mould wax + filter feed
eating tough food - leaves, wood, cereal grain, e.g. termites, grain beetles, ants
defence + competition - defend territories (ants) or compete for females (stag beetle)
May incorporate metals, e.g. zinc, manganese in cuticle of mouthparts

move from side to side

Question 8

What are the maxillae? function? movement/work? parts of the maxillae?

Answer 8

second pair of feeding appendages

used for handling food + sensing

work similar manner to mandibles

cardo, stipes, subgalea, lacinia, galea, maxillary palp

Question 9

What is the Labium? what is it similar to in humans? evolved from? parts of the labium?

Answer 9

fused 3rd pair of feeding appendages that close mouth below or behind

similar to lower lip

evolved from paired maxillae-like structures fused along centre line

submentum, mentum, prementum, glossa, palp, paraglossa
can be fused to form a ligula

Question 10

What is the hypopharynx?

Answer 10

mostly membranous ‘tongue’

projects forward from back of pre-oral cavity

salivary ducts at base

highly modified in Diptera + Hemiptera as main feeding organ

combines with rest of mouthparts to form stylet

Question 11

What are mouthpart modification due to?

Answer 11

feeding strategy

Question 12

3 different names for the position of mouthparts

Answer 12

Prognathous
Hypognathous
Opisthognathous

Question 13

Prognathous

Answer 13

head positioned vertically aligned with body

e.g. Coleoptera

Question 14

Hypognathous

Answer 14

head aligned horizontally adjacent to body

e.g. Orthoptera

Question 15

Opisthognathous

Answer 15

positioned diagnally

e.g. Hemiptera

Question 16

Mandibulate vs haustellate

Answer 16

mouthparts vary between insects of different orders
2 main functional groups: mandibulate + haustellate

Haustellate - sucking liquids + further classified by presence of stylets, incl:
- piercing-sucking
- sponging
- siphoning
Stylets = needle-like projections to penetrate plant + animal tissue
Stylets + feeding tube form modified mandibles, maxilla, + hypopharynx

Mandibulate - many different types
- plant chewing mouthparts
- predatory chewing mouthparts
- nectar/pollen collection

Question 17

Mandibulate - plant chewing mouthparts

Answer 17

primitive mandibulate mouthparts directed downwards
2 powerful mandibles, usually lined with teeth, work sideways
chewing insects have 2 lips:
1. Upper lip (= labrum) is flap, hangs down over mouthparts + covers mouth from front
2. Lower lip (= labium) covers mouth from behind

e.g. Adult Orthoptera, Coleoptera, Blattodea

Question 18

Mandibulate - Predatory chewing mouthparts

Answer 18

primitive mandibulate mouthparts directed forward

mandibles long + curved w/ sharp tips for impaling

ground beetle

modified mouthparts:
- dragonfly mouthparts typical except for labium
- swings forward to catch prey
- at rest forms a mask over all other mouthparts

Question 19

Modified for nectar/pollen collection

Answer 19

• utilise liquids + solids
• proboscis for lapping liquids & for exchanging food w/ other bees
• mandibles used to chew wood, manipulate wax, clean + bite other bees or pests (mites)

adult honey and bumble bees

Question 20

Haustellate - Sponging Mouthparts

Answer 20

proboscis (modified labium) = lowered + salivary secretions pumped onto food

dissolved food moves into pseudotracheae (sponge) + is ingested

sharp teeth on pseudotracheae to rasp flesh + draw up blood

Labellum functions as sponge-like organ to sop up liquids

Adult Diptera

Question 21

Haustellate - Siphoning Mouthparts

Answer 21

Proboscis (modified maxillary galeae) uncoils and extends sucking nectar into mouth or oral cavity

Adult Lepidoptera

Question 22

Haustellate - Piercing/Sucking Mouthparts

Answer 22

mandibles + maxillae formed into stylets, enclosed by labium

once stylets penetrate, secretion injected:
- blood-sucking - anaesthetic and anticoagulant, e.g. Rhodnius, Mosquitoes
- predacious - enzymes + toxins, e.g. Anthocoris, Assassin bugs

e.g. Hemiptera

Question 23

Mosquito mouthparts

Answer 23

Haustellate mouthparts of mosquito female highly modified for piercing skin + sucking blood

males have similar mouthparts but feed on nectar

Labium slides back towards head

mandibles + maxillae exposed + pierce skin

sensory organs on tips confirm host

Question 24

What are antennae?

Answer 24

• paired sensory appendages on head
• located between or below compound eyes

Question 25

What is the function of antennae?

Answer 25

provide greater surface area for sensory receptors
may detect:
- sound vibrations
- wind speed
- humidity

Question 26

Antennae structure

Answer 26

• Antennal socket (Torulus)
• Antennal sclerite
• Antennifer
• Antennal suture
• Scape
• Pedicel
• Flagellum

Question 27

Antennal morphology

Answer 27

used in taxonomic classification

males usually have more elaborate antennae

greater surface area of antennae, more dilute scents detected

male insects w/ feathery antennae, e.g. moths, far more sensitive than filamentous ones of crickets and cockroaches

Question 28

Geniculate

Answer 28

elbowed
e.g. weevils, bees + ants

Question 29

Lamellate

Answer 29

nested plates
e.g. Scarab beetles

Question 30

Pectinate

Answer 30

• comb-like
• E.g. Male glow worms

Question 31

Plumose

Answer 31

Brush-like/feathery
e.g. mosquitos and moths

Question 32

Clavate

Answer 32

Gradually clubbed
Carrion beetles

Question 33

Capitate

Answer 33

Abruptly clubbed
butterflies

Question 34

Setaceous

Answer 34

• bristle-like
• Dragonflies

Question 35

Filiform

Answer 35

• Thread-like
• Ground beetles and cockroaches

Question 36

Moniliform

Answer 36

Beadlike
Termites

Question 37

Serrate

Answer 37

Saw-toothed
Click beetles

Question 38

Aristate

Answer 38

Pouch-like with bristles
e.g. Housefly