|scientific name Pieris rapae |
common name Cabbage White
Ubiquitous throughout the province, particularly near agricultural habitats.
Occurs in multiple generations from April into September.
This is the only species of white which has both unmarked hindwing undersides and at least one black spot on the forewing upperside and the leading edge of the hindwing upperside. Royal Alberta Museum page
Like other Pieris species, the eggs are yellow and conical, with longitudinal ridges. Mature larvae are green with a pale dorsal stripe, and pupae range in colour from brown to green (Guppy & Shepard 2001). The first Cabbage Whites usually emerge in late April from hibernating pupae. There are usually three generations per year in Alberta (Bird et al. 1995). Up to four occur in southern BC, with development time of each generation varying from 4 to 8 weeks according to temperature (Guppy & Shepard 2001).
Not of concern.
Larvae sometimes reach pest status on cultivated mustards such as cabbage, broccoli, cauliflower and canola. A large number of Brassicaceae have been recorded as hosts, particularly introduced, weedy species (Guppy & Shepard 2001).
The Cabbage White was introduced from Europe to Quebec in the 1860's (Layberrry et al. 1998), and has since spread over all of North America with the exception of the Arctic and some of the extreme southern parts of the U.S. (Opler 1999).
Joe Belicek (2014-05-12)
Pieris rapae (Linnaeus, 1758) - Small Cabbage White
(a) In Alberta, the introduced Small Cabbage White butterfly is a member of the genus Pieris Schrank, 1801, The genus Pieris and the name is based on the Eurasian type-species Papilio brassicae Linnaeus, 1758. The genus contains ca. 40 species, geographically found in northern hemisphere. The remarkable adaptation of these butterflies is the chemical association with glucosinolates (mustard glykosides) found in the plants of the mustard family (Cruciferae or Brassicaceae). The Pieris caterpillars are able to detoxify the toxic glucosinolates, and will not eat any foodplant not containing glucosinolates. In fact, the Pieris females, detect the presence of glucosinolates before laying eggs on any food plant. In Alberta, the caterpillars feed the wild (Raphanus, Draba, Sysimbrium, Brasicca, Arabis spp. & others), as well as cultivated crops (cabbage, cauliflower, broccoli, mustards, radishes or ornamental cabbages. At times, and in certain places, the crop-damage caused by the feeding larvae of Cabbage butterflies is often considerable.
(b) During the previous century, Pieris rapae was accidentally introduced by commerce from Europe to North America, Australia, New Zealand, and Hawaii. Subsequently, the species established local populations and spread throughout the new territory.
(c) Voltinism, bio-topic/habit association, occurrence: (multivoltine, 2-3); ruderal, ubiquitous, doing well in Agri-monoculture. In Edmonton area, initially not overly-abundant, the Small Cabbage White, becomes as the season progresses the most common butterfly.
(d) In the Edmonton area, the first specimens are normally emerging in early May from the overwintering pupae.
(e) Affinities: Based on overall similarity and shared food plants in the mustard fimily, the most closely related genus to Pieris is probably the genus Pontia Fabricius, . According to Guppy & Shepard (2001): - 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 back discal cell spot that is lacking in the genus Pieris. It should also be noted that Pieris females typically lay eggs singly on the undersurface of the food plant leaves, whereas Pontia females typically lay eggs at the base of the flower buds of the food plant. It seems, that the larvae of Pontia preferably eat the flowers.
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