To infest or exploit as a parasite. The wasp larvae parasitize the caterpillars, feeding on them until they mature.
To habitually exploit or take advantage of someone or something. He tends to parasitize his friends for money and favors without giving anything in return.
To live or behave as a parasite, obtaining sustenance at the expense of another organism or host. Certain mite species parasitize throughout their life cycle, drawing nutrients directly from their hosts.