Lice Life Cycle: Introduction to Lice, Stages in the Lice Life Cycle, the Egg
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Introduction to Lice
Louse (plural: lice) is the common name for members of the order Phthiraptera.
Lice were ubiquitous in human society until at least the middle ages.
They contain 5,000 species of wingless insect.
They are obligate parasites living externally on warm-blooded hosts.
This includes every species of bird and mammal, except for monotremes, pangolins, and bats.
They are vectors of diseases such as typhus.
Head Louse
Life Cycle Stages
Life Cycle Stages
Stage 1
The Egg
The eggs are tiny particles and known as nits.
The egg can measure up to 0.8 mm, oval-shaped and yellow or white colored.
It takes around one week at least for the egg to hatch into nymphs.
Stage 2
The Nymph
Lice undergo three stages of moulting.
These are the tiny versions of lice.
It is yellow to white colored.
Stage 3
The Adult
The adult lice measure up to 2 mm in length.
The life span of adult lice is 30 days that too if it is fed frequent blood meals on a regular basis.
Evolution
Anoplura
Sucking lice
Occurring on mammals exclusively.
Rhynchophthirina
Parasites of elephants and warthogs.
Ischnocera
Mostly avian chewing lice.
One family parasitizes mammals.
Amblycera
A primitive suborder of chewing lice.
Widespread on birds.
They live on South American and Australian mammals as well.
Other Important Points
Humans host two species of louse namely the head louse and the body louse.
The body louse has the smallest genome of any known insect.
Chewing lice:
Live among the hairs or feathers of their host.
Feed on skin and debris.
Sucking lice:
Pierce the host’s skin.
Feed on blood and other secretions.
They usually spend their whole life on a single host.
Colour of the Lice:
Usually cryptically colored.
To match the fur or feathers of the host.
Colour varies from pale beige to dark grey.