Explanation of Names
RAPAE: from the Latin "rapa" (turnip);
Cabbage (
Brassica oleracea) and other members of the genus such as
Brassica rapa (commonly known as Field Mustard or Rape) are members of the mustard family (Brassicaceae, formerly Cruciferae), which are the larval food plants
Numbers
abundant in many parts of its range
Identification
Adult: upperside of wings white or pale yellowish-white with black tip on forewing; upperside of female forewing has two black spots; male has one. Both sexes have one black spot well out along front margin on upperside of hindwing.
Underside of forewing white with yellowish apex and two black discal spots in both sexes; underside of hindwing uniformly pale yellow in both sexes.
Larva: green or bluish-green with thin yellow dorsal line (sometimes faint or absent) and lateral line composed of pairs of yellow spots, the anterior spot of each pair with a black central dot; body covered with short fine hair.
Range
Throughout North America
(1) and many parts of the world.
Habitat
All habitats, including bogs, meadows, woods, and backyard gardens. Prefers open spaces but may also be found in treed areas, as noted above.
Season
Adults fly from early spring to September
(1); mid-April to mid-October in southern Ontario; shorter season farther north, and longer season farther south
Food
Caterpillars eat cabbage and many other crucifers and related plants.
(1)
Adults nectar from a very wide array of plants, including mustard, dandelion, red clover, aster, and mint.
Life Cycle
Females lay single eggs on undersides of host leaves. Overwinters as a pupa inside a chrysalis attached to some substrate. Two or three generations per year in southern Canada; up to several generations in the southern states.
Remarks
Introduced accidentally near Montreal in the 1860s, this species has become an important pest. Bacterial and viral diseases now provide some biological control.
(1)See Also
Best distinguished from other whites by the black spots on the upperside of the forewing, and the yellow hindwing below.
Internet References
pinned adult images showing upperside and underside of wings of male and female (Butterflies of Canada)
pinned adult image of female, plus description, biology, range, food plants, US distribution map (Butterflies and Skippers of North America, nearctica.com)
pinned and live adult and larva images plus description, distribution, abundance, flight season, habitats (Butterflies of Canada)
live larva image (Jay Cossey, Ontario)
live larva image (M. & P. Coupar, Museum Victoria, Australia)
live chrysalis image (John Capinera, U. of Florida)
