This document provides a classification and overview of important arthropods that can transmit diseases to humans and animals. It discusses the orders, families, and key genera of medical and veterinary significance. Some of the arthropods summarized include mosquitoes, black flies, horse flies, tsetse flies, sand flies, bed bugs, and house flies. For each group, it describes morphology, life cycle, disease transmission, and control methods. The document emphasizes that understanding the classification and biology of different arthropod vectors is important for prescribing effective control measures.

1. CLASSIFICATION
ARTHROPODS OF MED
ANDVET IMPORTANCE
MEDICAL ANDVETERINARY ENTOMOLOGY

2. INTRODUCTION
• Members of phylum Arthropoda constitute the largest number of
individuals and species
• Members of class INSECTA,
order Diptera
• 127 families, >85,000 species.
• Diptera - most important
vectors human disease.
! > 1 million deaths p.a.

3. SIGNIFICANCE OF ARTHROPODS
ASVECTORS
• The disease agents transmitted by various arthropods vary
widely in size and degree of pathogenicity.
• The manner in which various organisms parasitic to humans
and animals are transmitted dictates the type of association
the arthropods establish with the parasites

4. CLASSIFICATION
• CLASS: INSECTA
• Have six feet, their mouthparts are either chewing or piercing-
sucking mouthparts.
• Understanding nature of mouthparts is important in
prescribing control measures.
• The adult legs are attached to thorax, a pair in each segment,
each leg is composed of five jointed segments.
• The immature forms may have more legs or lack them
altogether.

5. ORDERS UNDER CLASS INSECTA
• There are three important orders
1) DIPTERA (flies): Families:Tabanidae (horse flies),
Culicidae (Mosquitoes), Simulidae (black flies),
Psychodidae (sandflies), Glossinidae (Tsetse flies) etc
2) ANOPLEURA (Lice)
3) Siphonoptera (fleas)

6. FAMILY: SIMULIIDAE
BLACK FLY
• Breeds close to fast moving water or water falls
• Eggs are laid on running water, larvae attach on submerged
structures e.g. rocks, trees & vegetation
• They are dark and bulky with clear wings and short antennae
Female flies
– Vicious biters & cause major distress to poultry, livestock & humans
– Cause extreme pain, itching & local tissue swelling
– Vast swarms cause livestock deaths via blood loss, suffocation
1-3mm

7. • ANATOMY
– Small (2-5 mm) stocky grey-black flies
– Humped thorax (buffalo gnats)
• LIFE CYCLE
• eggs are laid on plants or stones under rapidly flowing water.
• Development times are dependent on water temp

8. • Anatomy
– Small (2-5 mm) stocky grey-black flies
– Humped thorax (buffalo gnats)
• Life history: eggs are laid on
plants or stones under rapidly
flowing water. Development
times are dependent on water
temp

9. MED ANDVET IMPORTANCE
1) Allergic reactions. "Blackfly fever"
2) Vector - Onchocerca volvulus – filarial nematode that causes
‘river blindness)
3) Vectors - Leucocytozoon spp. - "malaria" in birds.
4) Females are blood-feeders
– Vicious biters & cause major distress to poultry, livestock &
humans
– Cause extreme pain, itching & local tissue swelling
– Vast swarms cause livestock deaths via blood loss,
suffocation & trauma

10. FAMILY: TABANIDAE
• They are all large flies : eg.Tabanus flies, horse flies
• The females attack animals and cause them much restlessness
1) Eggs are laid in the crack of soil and the wall, or hole. Under suitable conditions,
eggs hatch to larvae within 6 to 12 days.
2) Larvae feed on organic material.
Life cycle
1) There are four larval instars.
2) Pupae neither feed nor do activities. After 6 to 10 days, they emergent the adult
3) Adult- gonotrophic cycle requires about 6 days after feeding to develop ova.
4) Females only mate with males one time within life time, male will die after
mating, and female scan live 2 to 3 weeks.
18-22mm
18-22mm

11. BIOLOGY OF HORSE FLIES
• Biology
– Adults feed on nectar & plant juices;
females take vertebrate blood
– Larvae develop in moist habitats, often in
mud at edges of water bodies
– Most larvae feed on decaying plant matter;
some are predaceous

12. MEDICAL ANDVET IMPORTANCE
• Females are voracious blood-feeders (violently abrading skin to
create a pool of blood
– Serious pests of livestock (suffer weight loss)
– Also bite humans
– Transmit several parasites
• Protozoa → surra (cattle, horses, camels)
• Bacteria → tularaemia & anthrax (humans)
• Filarial worms → loiasis (humans) transmit (transmitted
by Chrysops – horse/deerflies)

13. FAMILY:CULICIDAE (MOSQUITOES)
• There are some 3530 species of mosquitoes, which are traditionally placed
• Have worldwide distribution
• Many mosquitoes which are not vectors can nevertheless be troublesome because of
the serious biting nuisances they cause
MORPHOLOGY
• Posses only one pair of functional wings, the fore-wings.
• The hind-wings are represented by a pair of small, knob-like halteres.
• Mosquitoes are slender and relatively small insects, usually measuring about 3–6mm
in length.
• Some species, however, can be as small as 2mm while others may be as long as 19
mm.
• The body is distinctly divided into a head, thorax and abdomen.

14. • The head has a conspicuous pair of kidney-
shaped compound eyes.
• Between the eyes arises a pair of filamentous
and segmented antennae.
• In females the antennae have whorls of short
hairs (i.e. pilose antennae
• The wings are long and relatively narrow, and
the number and arrangement of the wing veins
is virtually the same for all mosquito species.
The abdomen is composed of 10 segments
Important mosquito genera
- Anopheles
- Aedes
- Culex
- Mansonia
- Psorophora

15. BIOLOGY
• Almost all are blood-sucking; only females take blood; males take nectar
& plant juices
• Eggs laid in flowing or still water; water collected in containers, tree
cavities & leaf axils of plants
• Eggs laid singly or together in floating raft
• Larvae & pupae are aquatic; active swimmers & breathe via siphon tube
• Adults usually close to breeding sites
• Biting behaviour The biting behaviour of female mosquitoes may be very
important in the epidemiology of disease transmission. Mosquitoes feeding
on people predominantly out of doors and late at night
• Generally the behaviour of both people and mosquitoes may be relevant
in disease transmission.

16. LIFE CYCLE
1) Eggs are laid in the crack of soil and the wall, or hole. Under suitable
conditions, eggs hatch to larvae within 6 to 12 days.
2) Larvae feed on organic material. There are four larval instars.
3) Pupae neither feed nor do activities. After 6 to 10 days, they emergent
the adult
4) Adult- gonotrophic cycle requires about 6 days after feeding to
develop ova. Females only mate with males one time within life time,
male will die after mating, and female scan live 2 to 3 weeks.

17. • All mosquitoes require water for the
development of the larvae and pupae, but
the adult live inland.
1) Eggs are laid in or near water but
never in open water. Females respond
to a number of environmental stimuli
in choosing places to deposit their
eggs.
2) Aedes lay their eggs in damp or tree-
hole etc, whereas Anopheles lays its
eggs in the fresh water, e.g., rice field.
Culex lay their eggs in different type
water, e.g., sewage etc.
3) Under the proper conditions, eggs
develop and hatch often within 2-3
days.
•

18. MOSQUITOES (ADAPTATION)
• they are both vector and ectoparasites
• They can be able to locate its host using odour cues and temperature
cues
• Have sharp proboscis for sucking blood
• Mosquitoes suck blood more than during their life time hence they
can easily carry the parasites and transmit from one host to the next
• They can easily develop drug resistance thus allowing survival of the
various mosquito species
• Provide good environment in their bodies for the development of the
parasites

19. CONTROL OF MOSQUITOES
1) Protective measurs
- Use of treated nets
- Protective clothing
- Repellants
2) Larval control
3) Adult control
4) Intergrated pest control

20. MED ANDVET IMPORTANCE
• Transmit several parasites
" Protozoa (malaria)
" Filarial worms (elephantiasis)
" Arboviruses (yellow fever, dengue fever, encephalitis)

21. FAMILY: GLOSSINIDAE;
GENUS; GLOSSINA
TSETSE FLY
• The tsetse are blood-sucking insects,
in which both sexes partake, bite
during the day and night when the
moon is bright. They occur most
abundantly along heavily wooded
watercourses. Others in dry areas
• They are brownish black flies with
constricted waist. The wings when at
rest are closed scissors-like and
project beyond the abdomen. The
arista has branched hairs on its
upper surface, and the wing venation
is characteristic, there being a
striking " hatchet-shaped" cell in the
centre of the wing. Females incubate
single maggot in their bodies, larvae
pupate in soil; very soon after
deposited

22. FLIES - TSETSE FLY
Family Glossinidae, genus Glossina.
• Tsetse flies occur only in tropical Africa
• They are yellowish or dark brown, medium sized flies
• They can be distinguished from other large biting insects by
their forward pointing mouthparts
• They bite only in daytime.
• .

23. • Hosts & vectors of trypanosome
protozoans.
• Trypanosoma brucei species
complex.
• These flies transmit the
trypanosomes which cause sleeping
in man
• Sub-saharan Africa

24. ADAPTATION OF TSETSE FLIES
• both male and female flies feed on blood and therefore both can transmit
trypanosomes
• Offer a conducive environment in the thoracic muscles and the gut for the
development of the trypanosomes through the epimastigotes to infective
trypomastigotes which migrate to the mouthparts
• Glossina sp have a lifespan of 2-3 months therefore allowing the development of
the trypanosomes and their transmission
• glossina flies are ecologically adapted to different locales according to feeding
preferences and site choice for larviposition thus can survive competitions and
predation
• once the tsetse flies get infected with trypanosomes, they remain infected for
life

25. • The tsetse flies have long and sharp proboscis to easily
pierce the host skin
• They have the capability of locating their hosts in afar
distance using odour cues
• Usually takes more than one bloodmeal after every 4 days
for egg development therefore they can be able to transmit
the parasite from one host to another
• Glossina sp have strong wings and can fly for long distance

26. FLIES - SANDFLIES
Family Psychodidae
Phlebotomus & Lutzomyia species
• Less than 5mm length, hairy
body & wings
• Features: light or dark brown flies
and smaller than mosquitoes,
• Body and wings covered by dense
hair
• Though winged they only hop
about

27. MORPHOLOGY
• The legs are longer as compared to the size of the body
• They bite during night and only female bite; the males live on fruit juices
• Look like mosquito except their bodies are tiny, dark, hairy body, wings are hairy.
• The flies are 1-3mm
• The head bears a pair of long, slender and hairy antennae; short sucking proboscis.
• The thorax- humpback, with v shaped position of the wings at rest, Bears a pair of wings
and 3 pairs of legs. Wings are densely hairy and legs are very long out of proportion of
body.
• The ABDOMEN has 10 segment ccovered by hairs. In males 2 claspers are found in 10th
segment while female have 2 cerci
•

28. MED ANDVET IMPORTANCE
• Vectors of Leishmania - protozoa
• Cutaneous leishmaniasis (L. tropica
- Old World
• L. mexicana- NewWorld)
• Mucocutaneous leishmaniasis
(espundia) - L. braziliensis
• Visceral leishmanisis (kala azar) - L.
donovani
• Sand-fly fever (Papatasi fever/3
days fever)
• Oriental sore
• Oroya fever (Carrion’s disease).
• Annoyance constitute a serious, but
usually localized, biting nuisance

29. CONTROL
A. INSECTICIDES – Spraying with DDT & Lindane.
B. SANITATION- Removal of shrubs and vegetation, Filling u of
cracks and crevices in walls and floor

30. FAMILY: MUSCIDAE
HOUSE FLY
Musca domestica
• Domestic flies act as mechanical vectors of many disease Musca domestica is most
common house frequenting fly.
• It is non-biting. They act as mechanical vector for transmission of many diseases.
Identification features
• Head: It has a pair of compound eyes, a pair of antennae and a single proboscis on its
head
• Thorax: Has pair of wings and three pair of legs
• Abdomen: Segmented and shows dark and light markings

31. • Stomoxys
– Biting species – long piercing mouth parts
– Some species are aggressive & persistent blood-suckers (e.g. stable fly,
Stomoxys calcitrans)
– Torment wild & domestic animals (e.g. ears of dogs
• Life-history.-The eggs are laid in batches, in fresh horse manure, in human
feces, and occasionally in cow dung and garbage. The larvae which hatch
out moult twice, and the third-stage larval maggots migrate away and bury
themselves in the ground. Here they pupate, and the adults finally emerge
to the surface of the ground.

32. • Breeding habits:
• -Fresh horse manure
• -Human excreta
• -Manure of other animals etc
• Feeding habits: Can NOT eat solid foods. it vomits on solid
food to make a solution of it and sucks in a liquid state.
• Restlessness: This help in spread of infection mechanically.
• Resting habit: Rest on vertical surfaces and hanging objects.
• Dispersal: Normally remain close to breeding places but they
disperse frequently upto 4 miles.

33. MED ANDVET IMPORTANCE
1. Nuisance
• Large numbers flies can be bring significant nuisance by
disturbing people during work and at leisure.
• Flies soil the inside and outside of houses with their feaces.
• They can also have a negative psychological impact because their
presence is considered a sign of unhygienic conditions.

34. 2. Diseases
• Flies can spread diseases because they feed freely on human food
and filthy matter
• Flies pick up disease-causing organisms while crawling and
feeding
• Those that stick to the outside surfaces of the fly may survive for
only a few hours, but those that are ingested with the food may
survive in the fly’s crop or gut for several days
• Diseases that flies can transmit include enteric infections (such as
dysentery, diarrhoea, typhoid, cholera and certain helminth
infections), eye Infections (such as trachoma)

35. CONTROL
1. Environmental control
" Storing garbage & kitchen waste in bins with tight lids
" Provision of sanitary latrines
" Stopping open air defecation etc
• Insecticidal control
a) Residual sprays- DDT, lindane, malathion, fenthion etc
b) Space sprays- pyrethrin , DDT,HCH
c) Larvicide- diazinon, dimethoate

36. • Fly papers
" contains resin and castor oil
" applied to the stripes of wire and hung up in places where
flies abound
• Protection against flies
• - screening of house, hospitals, food markets etc
• Health education -Health education regarding disease
transmission and fly awareness

37. BUGS
• Class: Insecta
• Order: Hemiptera
• Family: Cimicidae ( bed bugs )
• Family: Reduviidae
• Sub-family: Triatominae
• 15 genera with > 100 spp
• Panstrongylus, Triatoma, Rhodnius

38. BED BUGS
• Family: Cimicidae
• Blood sucking
• Temporary ectoparasites of birds and mammals
• Human parasites:
• Cimex lectularis - main
• Cimex hemipterus
38

39. • Some groups of this order are winged and some are non-
winged. Include bedbug, assassin bug, kissing bug.
• True bugs vary in length up to 100mm, compound eyes and
usually large, antennae are 4 -5 segmented and often longer
than the head. The mouthparts are piercing-sucking with
segmented beak
• In most species the wings are present and positioned flat over
the abdomen when at rest the hind wings are membranous and
slightly shorter. Some bugs have reduced wings.
Metamorphosis is incomplete.

40. HABITS...
• Are easily transported in clothing and baggage
• In cold weather they remain inactive in hiding places
• They can survive starvation for over a year
• Emit a characteristic odour from scent glands
• Often found in dwellings with high rate of occupant turnover –
hotels, motels, hostels, shelters & apartment complexes

41. 41

42. HABITS
• They feed at night on humans or other mammals
• A blood meal is essential to production of eggs
• Conceal themselves during the day in crevices of wooden beds,
mattresses, or under loose wallpaper.
• In search for hosts, they respond to warmth & CO2, odours

43. TRIATOMINE BUGS
Family: reduviidae
Sub-family: triatominae
• Cone nose/assassin/kissing bugs
• Medically important, only found in americas
• Size: 1-4 cm long
• Elongated head
• Lateral 4- segmented antennae
• Eyes lateral

44. LIFE CYCLE…
• Both nymphs and adults feed nocturnally
• Feed on exposed parts of the body: face,
eyes, nose, mouth - kissing
• Defecates during feeding
• Feed on humans, wild and domestic animals.