1. Entomology
By Dr. Fan dong

3. Insecta Characteristics
Three body regions: the head, thorax, and abdomen. Each body region has specialized functions.
The head bears the mouthparts, the eyes, antennae, and other sense organs, and it houses the brain.
The thorax is the locomotory unit bearing the three pair of legs and the wings.
The abdomen contains many internal organ systems, for example, the digestive tract, reproductive organs, and excretory system.
要有图示的，扫描就可以

4. External morphology

5. Insecta

6. External morphology

7. External morphology of a beetle

8. THE INSECT'S HEAD
The head capsule is a sturdy compartment that houses the brain, a mouth opening, mouthparts used for ingestion of food, and major sense organs (including antennae, compound eyes, and ocelli).  

9. Other insects’ heads
beetles
moth
truefly
mosquitoes

10. Grasshopper’s head

11. Lines and grooves in the head capsule
Ecdysial line: coronal suture usually runs along the midline of the vertex and splits into two frontal sutures as it extends downward across the front of the head capsule.  

12. Midcranial sulcus: Ecdysial line

13. Frontoclypeal sulcus： boundary of frons and clypeus

14. Frontogenal sulcus ：compound eye- mandible, boundary of frons and gena, Orthoptera and Dermaptera

15. Ocular sulcus：skeleton around the compound eye sink inside

16. Subgenal sulcus: between frontoclypeal sulcus and postoccipital sulcus

17. Occipital sulcus

18. postoccipital sulcus ：

19. Grasshopper’s head

20. Region on the insect’s head
Site on the head
Region name
Top
vertex
Front
Frontoclypeal area
Profile
Ocular sclerite
gena
Subgenal area
Back
Occipital area
Postoccipital area

21. Frons and clypeus
frons
clypeus

22. vertex
vertex

23. Insect tentorium-endoskeleton
Dorsal tentorial arms
Posterior tentorial arms
Anterior tentorial arms

24. Antenna The insect antenna consists of three kinds of segment:
the first proximal segment termed the scape
the second segment termed the pedicel
the larger group of similar distal segments collectively termed the flagellum

25. The joints connecting each flagellar segment are flexible but can only move passively, whereas those between the scape and the pedicel and between the head and the scape are supplied with muscles allowing them to move actively.
Thus, mechanoreceptors on the flagellum make actual contact with objects

26. Johnston's organ in pedicel (second segment) of antenna.
This organ is a collection of sensory cells that detect movement of the flagellum

27. Detection of object position may be computed centrally when the tactile outputs from the flagellum and the proprioceptive outputs from mechanoreceptors at the scape and pedicel are combined in the central nervous system.

28. Functions of antenna
As multimodal sensors for monitoring the chemical and physical environment.
Chemoreceptors on the antenna are important in searching for, recognizing and discriminating appropriate foods, mates and habitats.
Mechanoreceptors on the antennae play critical roles in avoiding sudden attacks by predators and in perceiving physical objects around an animal

29. The tactile sense from the antennae
may be especially important in nocturnal insects, which often have to recognize the physical environment in more-or-less complete darkness.
A particular behaviour seen in insects is that they move their antennae in an exploratory fashion during environmental searching

30. This active antennal movement (scanning) may provide tactile information about the physical environment that is more effective than the information that could be obtained by a walking insect with immobile antennae.

31. Antenna types

32. Filiform Antennae

33. Setaceous -- bristle-like Dragonflies

34. Plumose Antennae
moth

35. Whorled antenna
Mosquitoes

36. pectinate：elateridae

37. Capitate antennae

38. clavate antennae
Butterflies
Antlion

39. Moniliform -- bead-like
Termites are generally pale in color and have antennae that look like small beads in a string.

40. Serrate -- sawtoothed
pea weevil

41. Geninculate (elbowed ) antennae
Weevils and Ants

42. Aristate Antenna: house flies

43. Lamellate Antenna of Scarab Beetle

44. Antenna groove (x285)

45. compound eyes
The compound eyes are often the most prominent structures on the head of the insects that possess them, as is shown in the dragonfly below

46. Horse flies (order Diptera) have spectacular compound eyes

47. The compound eye is made up of thousands of sensory units called ommatidia, each of which has an hexagonal lens and 6-8 light sensitive cells.

48. Ommatidia of mosquito (x3080)
Each omnatidium has a limited field of view, but sensory information from adjacent ommatidia combines to allow for an image to be 'compiled' in the optic lobe of the insect brain

49. Compound Eye
In most insects there is one pair of large, prominent compound eyes.
It is composed of several units called ommatidia. There may be up to 30,000 ommatidia in a compound eye.
This type of eye gives less resolution than the vertebrate eye, but it gives acute perception of movement -important in flight.

50. ocelli ：When present, ocelli(either 2 or 3), detect low light or small changes in light intensity
The 'simple eye' of many adult insects which consists of a single bead-like lens.
Ocelli may also be absent in some insects
ocelli

51. It is believed that they help to find the sea-level or horizontal during flying.
We still not exactly sure their functions.
Compound eyes and ocelli on halictid bee (order Hymenoptera).

52. Mouthparts
Mouthparts have evolved for special needs for different insects.
They can chew, suck, pierce, lap, and sponge-up their food.
Grasshopper has the most primitive type of mouthparts for chewing.

53. Basically all other types of mouthparts are evolved from the chewing type.
The labrum is suspended from the clypeus and form the upper lip.
Their function is to help keep food in the mouth.
The mandibles are transverse jaws for cutting and grinding.

54. Behind the mandibles there is the maxillae.
The maxillae also function as a set of jaws for food manipulation.
The labium functions as a lower lip.
Maxillary palpus and labial palpus are used for touching, tasting, and sensing temperature

55. Types of mouthparts Chewing mouthparts Chewing –lapping mouthparts
Sponging mouthparts
Scratching mouthparts
Siphoning mouthparts
Grasping-sucking mouthparts
Rasping mouthparts
Piercing- sponging mouthparts
Piercing- sucking mouthparts

56. labrum mandible maxilla labium hypopharynx
Chewing mouthparts
labrum
mandible
maxilla
labium
hypopharynx
labrum
maxilla
mandible
labium
hypopharynx

57. Generalized Insect Head with Chewing Type Mouthparts

58. Labrum
The labrum is the 'upper lip' of the mouth; it is a broad plate structure that is an extension of the head.
The labrum helps pull food into the mouth.

59. Labium
The labium is the 'lower lip' of the mouth, made up of a fused set of jaws and is a true mouthpart (not part of the head).
The labium also consists of a pair of labial palps.

60. Labial palps
The labial palps are often covered with sensory hairs and scales and test whether something is food or not.

61. Mandible
The mandibles are a hard pair of jaws, with teeth and grinding surfaces that work sideways to chew and grind food.

62. Maxillae The maxillae (singular: maxilla) are the second pair of jaws with teeth and maxillary palps. The teeth work sideways, to select and chew food.

63. Maxillae structure
Cardo
Stipes
Galea
Lacinia
Maxillary palps

64. Maxillary palps The maxillary palps are sensory organs with tiny hairs and they also have organs of taste and smell.

65. Hypopharynx Dense hair on the wall Function： Sense of taste
Its muscle can control expand and contract : food can be delivered and swallowed

66. Modifications of Chewing Mouthparts
Elongate rostrum of chewing insect (Hollyhock weevil)
Chewing mouthparts of yellow jacket Wasp

67. Insects which have chewing mouthparts :
Orthoptera and Coleoptera: adults and larvae
Neuroptera: adults
Lepidoptera : larvae
Hymenoptera: most of adults and sawfly larvae

68. Mouthparts prolong

69. Piercing Sucking
proboscis

70. Insect which feed on plant liquid or animal blood
Mouthparts can pierce into host and absorb its body liquid.
Hemiptera, Homoptera and some mosquitoes in Diptera

71. Mandibles and maxillae are formed into stylets which are enclosed by the labium.
Once the stylets penetrate, a secretion is injected to dissolve tissue, act as a toxin in predacious species, or as anticoagulant for mosquitoes

72. Piercing Sucking of plant feeders (True bugs, aphids, scale insects)
Mouthparts are shaped to brace the proboscis (beak) as the needle like mouthparts (stylets) penetrate the leaf tissue.
The head is musculated with a cybarial pump that helps insect suck plant fluid

73. Labrum of cicada reinforces proboscis which is a tube made of the rolled up labrum(lower lip)
Mandibular stylets lay curved in the tube and are used to pierce the plant tissue

74. Maxillary stylets are contained within the mandibular tube and form 2 tube.
The salivary tube is used to secrete enzymes that prevent the plant phloem sieve tubes from sealing or plant tissue from suberizing.
The food channel is used to suck up the plant fluid.
Note that some predaceous bugs have a similar morphology that allows them to skewer insects and suck out their body fluids.

75. Piercing sucking blood feeder (female mosquito)
Note that the same mouthparts are used to produce a penetrating proboscis.
Adaptations are to allow continual tissue cutting by maxillary and mandibular stylets, while a much larger food canal is used to suck up the blood.
Salivary ducts are key to secreting anticoagulant enzymes.

76. Chewing-Lapping mouthparts
Adult honeybees and bumble bees. Mouthparts are modified to utilize liquid food, honey and nectar.
A central "tongue" is used to draw liquid into the body.
The mandibles are not used for feeding but function to cut floral tissue to gain access to nectar, for defense, and for manipulating wax.

78. Rasping mouthparts
Thrips have rasping mouthparts to scrape foliar surfaces so they can then consume the fluid exuded from the damage.
These insects have an unusual adaptation in that the mouth has 3 stylets and lacks bilateral symmetry.
The left mandible is modified into a stylet as well as the part of each of the maxillae (lacinea).

79. Siphoning mouthparts
Moths and butterflies. When feeding the proboscis is uncoiled and extended.
Nectar is sucked up into the mouth or oral cavity.

81. Note this modification is just for sucking nectar out of plants, and water out of puddles.
There is no need to pierce anything.
The curled tube of the mouth is formed by a specialized, musculated, part of the maxilla called the galea.

82. Sponging mouthparts
Found in adults of specialized flies. During feeding the proboscis (modified labium) is lowered and salivary secretions are pumped onto the food.

83. The dissolved or suspended food then moves by capillary action into the pseudotracheae (sponge) and is ingested.

84. There may be sharp teeth on the pseudotracheae to rasp flesh and draw up blood.
The labella is the fleshy distal end of the labium that functions as a sponge-like organ to sop up liquids

85. Grasping-sucking mouthparts
Neuroptera : adults and larvae have different kinds of mouthparts
Adults : chewing mouthparts
Larvae: grasping-sucking mouthparts
characteristics:
long and wide mandible with sharp tip, which is like a sickle
Very small cardo and stipe , developed galea like a fine sickle

86. Scratching mouthparts
Larvae of flies
Degenerative head draws back into prothorax
Degenerative mouthparts, only a pair hooks with which the larva could scratch food and take the juice and solid scrap

87. Mouthpart Orientation Hypognathous
Hypognathous (Ventral) –Many herbivores
Grasshoppers, caterpillars, tiger beetles

88. Mouthpart Orientation
Prognathous (Anterior) –Many Predators
Great for predators trying to eat an insect it catches. lacewing larvae

89. Fixed toward posterior (herbivore)
Mouthpart Orientation:Opistognathous
mouthparts directed toward posterior
Some Sucking insects, great for drilling through wood (Cicada)
Fixed toward posterior (herbivore)