Head lice eggs, also known as nits, can be both white and brown in color. When first laid by a female head louse, eggs are usually light yellow to tan. After hatching and as the nit casing ages, it becomes pearl-white or pale gray. Towards the end of the incubation period, the nit will appear brown or coffee colored.
What do head lice eggs look like?
Head lice eggs are tiny, measuring about 0.8 mm long or about the size of a knot in thread. They have an oval shape and are usually found close to the scalp, attached to the base of the hair shaft. Nits are firmly cemented to the hair strands using a waterproof, sticky substance produced by the female louse as she deposits her eggs.
Young, unhatched eggs are transparent when first laid, allowing the developing embryo inside to be seen. After hatching, the empty nit remains firmly attached to the hair.
Egg color through the incubation cycle
The color of lice eggs changes as they develop, from being laid to hatching:
- When first deposited, the louse egg is yellowish-white and difficult to see.
- As the embryo inside matures, the egg develops an opaque, pearly-white hue within 1-2 days.
- By day 6-9 of the incubation period, the egg has a chalky, grayish-white appearance.
- Eventually the egg takes on a brown, tan or coffee-colored tone.
This color change happens as the developing embryo becomes visible through the nit sheath. Towards the end of the incubation period, the brownish coloring comes from the nymph louse which can be seen inside the casings.
Why do the eggs change color?
There are a few reasons why head lice eggs change color over time:
- The nits turn white as they become firmer and opaque within a day or two of being laid.
- A grayish tint develops around 6-9 days as the baby louse inside matures and becomes more visible.
- The eyes of the developing nymph begin to show through the casing, giving it a brown-toned appearance.
- The nit sheath may absorb melanin pigments from the hair which gives a brown color.
In summary, the eggs transition from clear to white, gray and finally brownish as the baby louse develops over 6-11 days before hatching. Being able to identify the age and viability of lice eggs based on color can be useful when treating an infestation.
Can you see the louse embryo inside?
Through the transparent egg casing, the developing louse embryo starts becoming visible after about 5-6 days of development. At this stage, the eyes of the baby louse may appear as red or brown spots inside the nit.
By days 9-11 when the embryo has fully formed, its eyes, legs and body shape are discernible inside the discolored nit. Seeing a developed louse nymph inside the egg indicates it is close to hatching or viable.
Are white eggs dead?
Not necessarily. While it’s true that white or off-white lice eggs are unlikely to be viable or hatch, some may still contain a living embryo. Here are some pointers:
- Pearly-white or light gray eggs are usually unhatched eggs that are under 1 week old.
- Chalky-white or cream colored eggs are often non-viable or contain a dead nymph.
- The only way to be sure an egg won’t hatch is to manually remove the entire nit from the hair strand.
Brown nit casings are also empty husks left on the hair after the lice has hatched. So white and brownish empty nits don’t necessarily mean the eggs are dead, only hatched.
Can you see the nymphs move inside eggs?
Towards the end of the 6-11 day incubation period, the fully developed nymph louse may be seen moving inside the egg casing as it prepares to hatch. The best time to check for movement is when the nit has turned brown or tan.
Gently slide the nit off the hair and observe it under a microscope or magnifying glass. Live movement visible inside brownish eggs confirms they are viable and likely to hatch soon.
Conclusion
To summarize key points:
- Newly laid lice eggs are yellowish-white while mature, pre-hatching eggs take on a brown or coffee color.
- The color change happens as the baby louse develops eyes and becomes visible inside the translucent nit covering.
- Seeing a fully formed nymph in a brownish egg means it is close to hatching.
- White nits may still be alive so must be fully removed from hair to prevent hatching.
- Observing movement in brownish eggs confirms they are viable and likely to hatch soon.
Being able to identify the age and viability of head lice eggs based on their color can help optimize treatment. Both white and brown nits need to be removed thoroughly to get rid of an infestation.
