By Chris Williams on November 18, 2011.
Q. My great uncle lives in a very old apartment building and has always had a cockroach problem. Often when I visit him I see white albino roaches mixed in with the other regular brown roaches. Are these really albino roaches or is it a different kind of cockroach?
A. They’re not really “albinos,” in the usual sense of the word. In fact, all cockroaches turn into white roaches many times during their lives. What appears to be an albino cockroach is really a roach that has just shed its old skin.
Insects grow by leaps and bounds, not gradually. Because they essentially have their skeleton on the outside of their bodies, they have to molt or shed that hardened cover in order to grow. A German cockroach nymph will molt 6 or 7 times before it becomes an adult roach. During its last nymphal molt, it emerges as an adult cockroach, complete with sexual organs and wings. Each time the old skin (or cuticle) is shed, the new cuticle underneath appears as soft and white and takes several hours to “harden-up” and turn dark.
You rarely see the shed skins left behind by cockroaches after they molt. They are usually eaten quickly by the nymphs that emerge from them or by other cockroaches as they provide a good source of nutrients.
If they’re so common, why don’t we see “albino” roaches more often? Newly molted cockroaches are soft and vulnerable; they usually stay hidden in protected places until their new cuticle has hardened. In fact, they usually go into hiding a couple of days before they are due to shed their skin. Molting is a risky business and many insects die during the process either from predation or complications. The fact that you see white cockroaches often at your uncle’s indicates that he has a pretty heavy cockroach infestation and that these vulnerable roaches are being forced out of already occupied hiding places. White cockroaches don’t want to be out in the open if they can help it.