The exact date of when head lice eggs hatch remains a mystery. While most people are aware that a louse can live for up to 28 days, it’s not always clear exactly how long the eggs will remain viable. In order to determine the exact age of head lice eggs, it’s helpful to understand how long adult lice live. The life cycle of these insects includes 3 phases, starting with the egg, which takes six to nine days to hatch. These eggs must remain within four or six millimeters of the scalp to hatch. Lice eggs cannot survive further away than this distance. Once the eggs hatch, they become nymphs, which are similar to adult head louses. Adult lice can lay up to 10 eggs a day, which means that newly hatched eggs will remain viable for 12 to 14 days.
The location and temperature of the scalp play an important role in how long the eggs take to hatch. Warmer temperatures cause the lice to develop faster. The hair style also affects the hatching time of the eggs. Hair that is thick and near the nape of the neck and thinner hair on top of the scalp will make it easier for the lice to hatch their eggs.
Luckily, there are ways to eliminate the infestation and prevent its recurrence. One method is to use an oral insecticide. These products are highly effective and kill lice and their eggs. They should be applied to dry hair and washed regularly.