Pontia protodice

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 . 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. == 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. == Nectar plants ==

Checkered whites have been seen nectaring on mustards, composites, and alfalfa. == Host plants ==

The host plants for this species include Brazos rockcress (Arabis petiolaris), sicklepod (Senna obtusifolia), black mustard (Brassica nigra), broccoli (Brassica oleraceae italica), Brussels sprouts (Brassica oleraceae gemmifera), cabbage (Brassica oleraceae capitata), cauliflower (Brassica oleraceae botrytis), turnip (Brassica rapa), pinnate tansy-mustard (Descurainia pinnata), flixweed tansy-mustard (Descurainia sophia), prairie pepperweed (Lepidium densiflorum), Virginia pepper-grass (Lepidium virginicum), radish (Raphanus sativus), tumble mustard (Sisymbrium altissimum), and field pennycress (Thlaspi arvense). == Behavior ==

Sexual selection In order to increase their reproductive fitness, male P. protodice must select a female who will put his investment to good use. One trait that males select for is bigger size and longer forewing length. It is unknown whether larger females are preferred by males or whether larger females can simply be seen at greater distances than their smaller conspecifics. Males also tend to prefer younger females with whom they copulate for longer periods of time. The dorsal wing surface of females are partially ultraviolet reflective, especially in older females who have melanic markings. As females get older, they tend to accumulate tattering and scale loss which are consequences of increased contact with vegetation during feeding and their search for oviposition sites. Thus, their wings become worn. UV absorbing pigments located on these scales explain the changes in UV reflectance as a female becomes older. Males use this cue to evaluate the age of a female conspecific. It is quite a reliable cue, as the spermatophores of worn females tend to be completely collapsed and empty. Female advancements Males are efficient at finding females, making courtship solicitation by females rare. However, female P. protodice have been seen to actively approach and chase both conspecific males and females. When directed at other females, interactions last only a few seconds; however, when directed at males, this behavior is most likely an attempt to solicit male courtship. As a female flies about feeding and searching for oviposition sites, the contents of the spermatophore decreases in size, and the female becomes interested in re-mating. On average females deplete material received from males in 5 to 7 days. 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. This rejection posture has often been misconstrued as an invitation to mating, as other butterflies such as the Heliconius use it to attract mates. Sexual conflict in 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. 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. == See also ==