Lice, Fleas & Bedbugs

Question 1

3 species of Human Lice

Answer 1

Clothing, Head and Pubic/Crab

Question 2

Human Lice Key Features

Answer 2

• Adult size between 2 – 4 mm long
• Cream to dark brown
• Dorso-ventrally flattened
• Leathery cuticle
• Strong claws
• Eyes present

Question 3

Head/Clothing Louse Male vs. Female

Answer 3

Males - distinctive “tibial thumb” on the
foreleg, pointed tip to the abdomen, intromittent organ is on the dorsal surface
Female - lacks tibial thumbs, typically
longer and broader, tip of her abdomen is bi-lobed

Question 4

Clothing Lice Faeces

Answer 4

Dark, powdery and easily airborne

Question 5

Head/Clothing Lice Eggs

Answer 5

Oval with distinct low operculum

Distinguishable by location of egg

Question 6

Human Lice Mouthparts

Answer 6

Haustellum - tube-like structure at the front of the head

Hooks located within the haustellum secure the louse to the skin

Question 7

Head Louse Nymphs

Answer 7

Morphologically similar to the adults but lacking external genitalia

Question 8

Pubic/Crab Louse

Answer 8

More compact, squat body shape
Large claws on the 2nd and 3rd pairs of legs
2 fewer abdominal segments than Pediculus spp.
Distinct lateral processes

Question 9

Pubic/Crab Louse Male vs. Female

Answer 9

Male - tip of the abdomen is rounded and the external genitalia is dorsal
Female - abdomen is bi-lobed
No tibial thumbs present

Question 10

Pubic/Crab Louse Egg

Answer 10

Oval shape

Distinct raised operculum

Question 11

Flea Key Features

Answer 11

• Oval (1 – 8 mm long)
• Reddish brown to black
• Laterally flattened
• Shiny, waxy cuticle
• Combs, Mesopleural Rod in some species

Question 12

Combs

Answer 12

Genal or pronotal

Finger-like outgrowths

Question 13

Mesopleural Rod

Answer 13

Thickening of the ventral cuticle of the middle thoracic segment (mesopleuron)
Looks like an ice pick

Question 14

Fleas Male vs. Female

Answer 14

Males - smaller, upturned abdomen, genitalia are coiled within the body
Females - larger, smooth rounded abdomen, globular spermatheca is visible

Question 15

Flea Eggs

Answer 15

Small 0.1 - 0.5 mm and oval in shape

Smooth cuticle and a pearly-white colouration

Question 16

Flea Larva

Answer 16

Caterpillar-like appearance
Small heads with a pair of simple antennae and no eyes
Circle of setae on the rear edge of each body segment
Anal struts - two finger-like processes at the tip of the abdomen
No legs, 4 – 10 mm long

Question 17

Human flea (Pulex irritans)

Answer 17

• No genal or pronotal comb
• No mesopleural rod
• Head smoothly rounded
• Interantennal suture is thickened such that the flea appears to be wearing “headphones”
• Overall the body appears very smooth with fewer spines

Question 18

Cat Flea (Ctenocephalides felis felis)

Answer 18

• Both a genal comb and a pronotal comb are present
• Mesopleural rod is present
• Head often elongate
• Interantennal suture is present

Question 19

Northern Rat Flea (Nosopsyllus fasciatus)

Answer 19

• Presence of a pronotal comb but no genal comb
• Pronotal comb of 18 - 22 points
• Interantennal suture present
• Mesopleural rod is present

Question 20

Mouse Flea (Leptopsylla segnis)

Answer 20

• Presence of a pronotal comb
• Presence of a reduced genal comb of only four points
• Eyes are vestigial
• Head appears “folded back”
• Mesopleural rod is present
• Interantennal suture is well developed

Question 21

Tropical Rat Flea/Plague Flea (Xenopsylla cheopis)

Answer 21

• No genal or pronotal comb
• Presence of a mesopleural rod
• Interantennal suture is absent (no headphones)

Question 22

Fascicle

Answer 22

Piercing-sucking mouthparts of the flea
Ventrally placed and consist of 3 stylets
Pair of fine maxillary laciniae (serrated and
blade-like)
Single epipharynx (food canal)

Question 23

Proventriculus

Answer 23

Simple valve located at the entrance to
the flea’s midgut
Regulates the intake of blood and prevents its backflow into the oesophagus
Can be compromised by the growth of plague bacilli

Question 24

Jigger Flea (Tunga penetrans)

Answer 24

Small, 1mm long
Rounded, compact body
Thoracic segments are very compressed
Head has a distinct point on frons
Mouthparts are elongated
Hind coxa has a distinct angle

Question 25

Jigger Flea Male vs. Female

Answer 25

Males - less prominent mouthparts, smaller respiratory spiracles and angular genitalia that barely fit into the body
Female - long prominent mouthparts, large abdominal respiratory spiracles and a
rounded abdomen

Question 26

Bedbug Key Features

Answer 26

Oval (5 mm x 3 mm)
Yellow to dark brown
Dorso-ventrally flattened
Proboscis folded under head at rest

Question 27

Male Bedbug

Answer 27

More pointed abdomen than the females and are asymmetrical in outline.
The tip of the abdomen is off centre.
Curved/pointed intromittent organ at the apex of the abdomen

Question 28

Female Bedbug

Answer 28

Rounder abdomen, symmetrical in outline. On the ventral surface there is a distinct slit on the bug’s right hand side in the fourth abdominal segment (leads in to the organ of Berlese)

Question 29

Bedbug Egg

Answer 29

About 1 mm long, pearly white
or pale yellow and slightly curved at
the anterior end
Distinct operculum (lid) through which the
embryo respires

Question 30

Early instars of bedbugs

Answer 30

Pale yellow colour and can easily be overlooked due to their small size

Question 31

Common vs. Tropical Bedbug

Answer 31

Differentiated by examination of the pronotum

Question 32

Pronotum

Answer 32

Dorsal plate of the first thoracic segment and is very prominent in bedbugs

Question 33

Common Bedbug Pronotum

Answer 33

Lateral edges are flattened

Question 34

Tropical Bedbug Pronotum

Answer 34

Lateral edges of the pronotum are rounded

Question 35

Bedbug Mouthparts

Answer 35

Rostrum are tucked under the head when at rest
During feeding the rostrum is extended and the labial sheath folds back to reveal the delicate stylets that pierce the skin