Anopheles crucians is a mosquito of both permanent and semi-permanent waters. The species feeds on mammals and overwinters in the adult stage. Adults can be found resting under houses, bridges, in hollow trees, culverts, and other similar structures. A. crucians are principally outdoor biters, but may occasionally enter houses seeking a blood meal. Females attack mostly at night, but may attack during the day in shade or under cloud cover. The larvae develop in shaded, acid swamps, ponds, and lakes, and are generally associated with aquatic vegetation.