Lice, Fleas & Bedbugs Flashcards
3 species of Human Lice
Clothing, Head and Pubic/Crab
Human Lice Key Features
- Adult size between 2 – 4 mm long
- Cream to dark brown
- Dorso-ventrally flattened
- Leathery cuticle
- Strong claws
- Eyes present
Head/Clothing Louse Male vs. Female
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
Clothing Lice Faeces
Dark, powdery and easily airborne
Head/Clothing Lice Eggs
Oval with distinct low operculum
Distinguishable by location of egg
Human Lice Mouthparts
Haustellum - tube-like structure at the front of the head
Hooks located within the haustellum secure the louse to the skin
Head Louse Nymphs
Morphologically similar to the adults but lacking external genitalia
Pubic/Crab Louse
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
Pubic/Crab Louse Male vs. Female
Male - tip of the abdomen is rounded and the external genitalia is dorsal
Female - abdomen is bi-lobed
No tibial thumbs present
Pubic/Crab Louse Egg
Oval shape
Distinct raised operculum
Flea Key Features
- Oval (1 – 8 mm long)
- Reddish brown to black
- Laterally flattened
- Shiny, waxy cuticle
- Combs, Mesopleural Rod in some species
Combs
Genal or pronotal
Finger-like outgrowths
Mesopleural Rod
Thickening of the ventral cuticle of the middle thoracic segment (mesopleuron)
Looks like an ice pick
Fleas Male vs. Female
Males - smaller, upturned abdomen, genitalia are coiled within the body
Females - larger, smooth rounded abdomen, globular spermatheca is visible
Flea Eggs
Small 0.1 - 0.5 mm and oval in shape
Smooth cuticle and a pearly-white colouration
Flea Larva
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
Human flea (Pulex irritans)
- 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
Cat Flea (Ctenocephalides felis felis)
- Both a genal comb and a pronotal comb are present
- Mesopleural rod is present
- Head often elongate
- Interantennal suture is present
Northern Rat Flea (Nosopsyllus fasciatus)
- Presence of a pronotal comb but no genal comb
- Pronotal comb of 18 - 22 points
- Interantennal suture present
- Mesopleural rod is present
Mouse Flea (Leptopsylla segnis)
- 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
Tropical Rat Flea/Plague Flea (Xenopsylla cheopis)
- No genal or pronotal comb
- Presence of a mesopleural rod
- Interantennal suture is absent (no headphones)
Fascicle
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)
Proventriculus
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
Jigger Flea (Tunga penetrans)
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
