There are three phases to host selection by the "P. rapae" adult female butterfly: searching, landing, and contact evaluation. A gravid female adult will first locate suitable habitats, and then identify patches of vegetation that contain potential host plants. The cabbage butterflies seem to limit their search to open areas and avoid cool, shaded woodlands even when host plants are available in these areas. Furthermore, gravid females will not oviposit during overcast or rainy weather. In laboratory conditions, high light intensity is required to promote oviposition. The females fly in a linear path independent of wind direction or position of the sun. Pre-mating females do not display host plant searching behavior. The behavior starts soon after mating. Flight behavior of an ovipositing female of "P. rapae" follows the Markov process. Females foraging for nectar will readily abandon a linear path; they will show tight turns concentrating on flower patches. Females searching for host plant, however, will follow a linear route. As a result of directionality, the number of eggs laid per plant declines with increases in host plant density. The average move length declined as host plant density increases, but the decline is not enough to concentrate eggs on a dense host plant collard. Although females avoid laying eggs on plants or leaves with other eggs or larvae in a lab condition; this discrimination is not shown in field conditions. Adult females may search for a suitable Brassicaceae over a range of 500 m to several kilometers. Small differences in flight patterns have been observed in Canadian and Australian "P. rapae", indicating that there may be slight variation among different geographic populations. Landing appears to be mediated primarily by visual cues, of which color is the most important. "P. rapae" in a lab environment showed no significant preference for the shape or size of the oviposition substrate. Gravid females responded most positively to green and blue/green colors for oviposition. The preference was shown for surfaces with maximal reflectance of 550 nm. In natural conditions, oviposition was preferred on larger plants, but this was not reflected in laboratory conditions. Younger plants often had yellow/green color while older plants display a darker and stronger green. Female butterflies preferred the older plants due to the attraction to the darker green color. However, larvae perform better on younger plants. Once a gravid female lands on a plant, tactile and contact chemical stimuli are major factors affecting acceptance or rejection of the site for egg deposition.