How to Detect Head LiceInspect the hair and scalp for crawling lice or eggs. they're most commonly found at the nape of the nack and behind the ears. There are rarely more than 10 crawling lice at a time, so diagnosis is often made by finding the eggs. Be careful not to confuse hairspray, dandruff, or other debris with eggs. Unattached eggs will normaly be within 1/4" of the scalp's surface; hatched eggs will be 1/2" or more from the scalp.