Checkered white

Appearance

The upperside of the wings are white and marked with black and gray, more so on the female than on the male. The underside of the hindwings is marked with extensive yellow-brown veins. The wingspan is 1.25–1.75 inches . In its pre-adult form, the egg is orange, and mature larvae are black dotted and bluish green to gray with a yellow dorsal, lateral and sublateral stripe. The pupa overwinters, and varies in color from blue-gray to cream.

Distribution

''Pontia protodice'' is most commonly found in the southern parts on the United States along with some of the northern areas of Mexico. Occasionally the species can be found in the northern parts of the U.S. and southern Canada. It is absent from the Pacific Northwest and the New England area, although populations have become increasingly erratic just east of the Appalachians.''P. protodice'' are most widespread in late summer and autumn, not earlier in the season.

Behavior

In courtships, females land on exposed perches and the following major events occur: the male contacts the female, the male begins probing, the male abdomen comes between the female's hindwings, and lastly the male stops moving. Aside from many other butterfly species, ''P. protodice'' females lack an abdominal extension response. A male does nothing more than land on a female's thorax and couple with her. In half of all courtships, females also exhibit a low amplitude flutter response which seems to have no effect on the duration of copulation.

In addition, in situations where they want to fend off a male's advances, female ''P. protodice'' exhibit a rejection behavior, initiated as if they are aware of the presence of a full spermatophore. The female's wings are fully opened with the tips below the horizontal. In addition, the abdomen is elevated to 45-60 degrees above the body axis and the genitalia are extruded. This rejection posture has often been misconstrued as an invitation to mating, as other butterflies such as the ''Heliconius'' use it to attract mates.''P. protodice'' require elevated body temperatures of 30-40 degrees Celsius in order to fly, and this is achieved by behavioral orientation to solar radiation. ''Pieris'' butterflies, including ''P. protodice'' use a behavioral posture for thermoregulation called reflectance basking, in which the wings are used as a sort of biological solar reflector in order to reflect radiation to the body and increase body temperature. In the reflectance basking posture, the dorsal body surface is positioned towards the sun, and the wings are subsequently held open at an angle. The posture suggests that the butterfly is using its white dorsal wing surface to reflect radiation onto their bodies.

Habitat

Habitats are open areas, including desert, plains, and disturbed areas. Virtually any disturbed dry open area such as vacant lots, railroads, airports, dry grassland, deserts and cities are potential areas of inhabitation. In addition, populations may sometimes be found in sparsely wooded areas, grasslands, and meadows in the prairie and parkland regions, usually in areas without heavy shade. Though it may seem these species of butterfly inhabit a wide range of environments, they have been found to be absent from certain counties for many years at a time.

Migration

In general male pupae develop faster than their conspecific females, and as a result, eclose earlier in the season than females. In addition, they are typically ready to mate within 24 hours of eclosion. This is the reason why there seems to be a high ratio of males to receptive females. In this high-density environment, females are often harassed by males. They will be approached by more than one males at a time within seconds of flight, and the males will often remain in the vicinity for long periods of time. In this situation, females are forced down a gradient of male density, encouraging emigration out of the colony. They will emigrate and colonize new habitats in the process. It is only in instances of increased male death and still emergent females, late in the breeding season, that the numbers balance and no emigration occurs.