Becker's Whites are white with black markings above, and yellow veins broadly outlined in green on the ventral hindwing and the ventral forewing apex. The black discal cell spot is large and roughly square, and curves inward to follow the shape of the cross-vein at the end of the cell. Males have androconial scales in the discal cell spot. Spring and fall forms of Becker's Whites are smaller and darker than the summer form.
Eggs are columnar with vertical ribbing. Mature larvae are green white, thickly marbled or sprinkled with grey, and with orange yellow rings between each segment. Each segment has 16-18 black tubercles capped with bristles. The head is tinged with yellow. Pupae are roughly cylindrical and smooth, and are held against a stem with a girdle. They are grey, with the wings nearly white, and the top of the thorax is dark grey brown. There is a pale line along each side of the abdomen, and four black dots in a row across the back between thorax and abdomen (Mead 1878).
The type locality of Pontia beckerii is Virginia City, NV. There are no recognized subspecies. The spring form of P. beckerii was incorrectly named subspecies pseudochlorodice (McDunnough, 1928) (TL: Oliver, BC).
The name Pontia is from the Greek pontios, especially in reference to Aphrodite (Venus), the goddess of beauty, who was born from the sea. Pontia and Colias were both names associated with Aphrodite. Fabricius divided what we now call the family Pieridae into those that are yellow (Colias) and those that are white (Pontia), two related aspects of beauty. Fabricius was probably also referring to Linnaeus having originally included all white and yellow/orange butterflies in the group he called the Danai, with many species named after the 50 daughters of Danaus. The common name is shared with the genus Pieris and refers to the basic white colour of the wings. The common name for the genus was first used in North America by Scudder (1875), but apparently had been in use in Britain for the white Pieridae since at least 1717 (Warren 1990).
Whites in the genus Pantia are all medium-sized butterflies with white or pale yellow wings with black markings. A given species may look quite different at different elevations, latitudes, or seasons. They are usually smaller and darker in the spring, at high elevations, and in the north.
The eggs of whites are conical, with vertical ribs down the sides and numerous small horizontal ridges between the vertical ribs. The eggs are pale yellow when laid, but within a day or two turn bright orange. Eggs are laid singly on the leaves or flowers of plants in the mustard family (Brassicaceae), with the most commonly used native plants being in the genus Arabis. Mature larvae are smooth-skinned with a thin coat of fine hairs.
In the genus Pontia the cross-vein at the end of the forewing discal cell is strongly curved inward towards the wing base. This vein is white but is surrounded by a black "discal cell spot" that is lacking in the genus Pieris. There are grey green or grey markings following the venation on the ventral hindwings.
There are four species in the genus in North America, all of which occur in BC, and another six in Europe, Asia, and Africa.
All whites were included in the genus Pieris until relatively recently, but the differences between the groups of species appear to be great enough to separate them into two genera, Pontia and Pieris, based on morphological characters (Higgins 1975) and electrophoretic data (Geiger 1990). A third generic name sometimes applied to whites, Artogeia Verity, 1947, is a synonym of Pieris (Geiger 1990).
Becker's Whites are multivoltine in BC, with broods emerging from hibernating pupae in late April and additional generations emerging from pupae in early July, mid-August, and late September. There is considerable overlap between the later broods. Becker's Whites lay eggs on the flowerheads of Arabis, with the larvae feeding on the flowers and fruit of the inflorescence. Pupation occurs on the stem of the larval foodplant.
Outside BC foodplants are Brassicaceae such as Arabis, Brassico nigra, Descurainia sophia, Lepidium perfoliatum, Sisymbrium loeselii, Stanleya pinnata, Streptanthus, and Thlaspi (Emmel et al. 1971; Howe 1975; Ferris and Brown 1981). In California Cleome isomeris (Capparidaceae) is also a major foodplant (Hovanitz 1962). The Cleome remains green even under very arid conditions, and may permit the multiple broods of the Becker's White (Hovanitz 1969).
Becker's Whites inhabit the arid lowland grasslands of the Southern Interior of BC.
Becker's Whites occur from the Southern Interior of BC south to Baja California east of the coastal mountains and in south coastal CA. They extend east to MT, WY, CO, and NM.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
22/11/2019 12:15:56 PM]
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