Do head lice prefer clean hair?
I remember overhearing this when I was knee-high to a grasshopper and thinking that, at last, I had the excuse I needed to banish bathing once and for all. Parental authority had other ideas, for which I am thankful — not just because the advantages of clean habits dawn on you with the arrival of adulthood, but because it turns out head lice aren’t as picky as I had heard.
At least as far as I can tell. Head lice are one of those medical curiosities that, while widespread and irritating, aren’t dangerous or interesting enough to attract a lot of scientific scrutiny. Your typical medical researcher doesn’t dream of holding in their hand the cure for lice, they set their sights on cancer, Alzheimer’s and other big hitters — and probably rightly so. Lice and the nits they leave behind are annoying but not life-threatening. But the lack of scientific interest does allow all kinds of nit-wit claims and lousy ideas to spread.
Head lice aren’t very good with curly hair, probably because the cross-section of naturally curly hair is challenging for them to get a grip on. That doesn’t stop them trying, though.
As for cleanliness, there isn’t any evidence that head lice prefer clean or dirty hair. They just don’t care what kind of hair they grab on to: as long as it is hair they will get their hooks into it and do their best to stay put. These critters are after blood, after all. How picky are they going to be about whether you shampooed in the last 24 hours?
Mind you, it isn’t a crazy idea. Some infectious diseases really do spread better among cleaner populations than dirty ones. And one could imagine that the accumulation of grime and oil on dirty hair might make it hard for the little bloodsuckers to hold on. But it just isn’t so.
Head lice aren’t all that fussy about their accommodation. Dirty hair is no protection and clean hair isn’t an open invitation. You don’t need to worry that your lustrous locks will leave you lousy.