Observations by tharcikatharmabala

Scientific and Common Name
Scientific name: Pieris rapae Common Name: Cabbage White Butterfly.
Habitat and Geographic range
Pieris rapae is an invasive species originating from Europe. Pieris rapae was introduce in Quebec city, New York City, Chicago, Florida, Charleston and Indiana and has since spread through North America. After the initial invasion of P.rapae in Quebec city the species begun to spread through west Quebec and into Ontario at a rate of 42.6 +3.0 kilometers per year, more information including geographical diagrams and statistical evidence of the dispersion of P.rapae can be found in Spread of invading organisms (Andow, Kareiva, Levin, & Okubo, 1990). These species can still be found throughout Europe and Australia (Jones, 1987). The invading species have adapted to live in a variety of habitats including grasslands, Tallgrass, foothills of Grasslands and Riparian, Montane woodlands and Plains Riparian (Robinson, Armstead, & Deane Bowers, 2012). In a study done by Robinson et al confirmed that P.rapae was more commonly found in Plains Riparian site where P.rapae composed of 89% of the butterfly population recorded in their study (Robinson, Armstead, & Deane Bowers, 2012).
Size/Weight and Lifespan
The size of the P.rapae above is roughly 60 mm in length and 50mm in width with a tear in the top left wing. The weight of the P.rapae above, although not officially weighed, would approximately weigh between 2-3 grams. The lifespan of P.rapae begins when the female lays her eggs on a host plant. After the eggs hatch, the caterpillars remain on the host plant for 10-20 days until it reaches metamorphosis. Once P.rapae has transformed into its final stage of life it is ready to mate. The female of this species can live to three weeks after laying her eggs (Gilbert,1984).. In the study conducted by N. Gilbert, there is evidence that larger P.rapae survive better at every stage of life and can lay more eggs than smaller P.rapae (Gilbert, 1984). P.rapae can live up to five generations in a year (Jones,1987).
Diet
Juvenile P. rapae consume nutrients that are in the host plant that the parent P.rapae has chosen for them. These host plants are typically a wide selection of wild and domesticated species of the Brassica genus or the mustard genus (Kingsolver, 2000). Adult P.rapae consume protein rich pollen from nearby angiosperms (Wiklund, Karlsson,& Leimar, 2001).
Reproduction & Communication
Reproduction in the P.rapae species occurs during the autumn months of the year, when the female is able to absorb certain UV rays between 380-400 mu and reflect them in her wings, communicating to the males that the female is ready to mate (Obara,1970). In an experiment by Obara they discovered that male P.rapae are able to easily differentiate between males and female. They set up fake male and female dummies and recorded the number of times the dummy was visited. The female dummy was visited 106 by males and the male dummy was virtually not visited at all (Obara,1970). When the female signals that she is ready to copulate, she is in a resting position on a plant leaf or the ground. There is no visible or apparent forms of courtship (Obara,1970). If the female has already mated or is refusing to mate with the male, she will open her wings and arch her abdomen so that it is perpendicular to the ground (Obara,1970). Once the female is impregnated she will find a suitable host plant and lay her eggs, where they will hatch and remain on the host plant until the juveniles reach metamorphosis (Kingsolver, 2000).
Predators
P.rapae have numerous natural predators notably insect parasitoids, social wasps (Jones,1987), and different species of birds, including garden warblers, tits and house sparrows (Baker, 1970). In the experiment conducted by Robin Baker, bird predation on P.rapae was recorded. They discovered that house sparrows and tits were the main predators of P.rapae (Baker,1970). In another study conducted in Australia, researchers concluded that ant predation has a significant impact on the mortality of P.rapae, However ant predation is effected by season and location, and P.rapae can have four to five generations per year, allowing at least one generation of P.rapae to be ant predation free (Jones,1987). The study also demonstrates evidence that parasitized P.rapae by braconid wasps were more heavily preyed upon than non-parasitized P.rapae (Jones,1987).
Conservation Status
The P.rapae being able to produce four to five generation per year, its successfully invasion of North America, and its ability to continually adapt to ecological niches, has increased its presence throughout the world, and is safe from any threat to the species’ survival (Kingsolver, 2000).
Fun Fact
Did you know that P.rapae gets its common name Cabbage White Butterfly from the P.rapae using various domesticated species of cabbages as host plants when laying their eggs? As P.rapae do not leave their host plant, most cabbages become infested with P.rapae and they are considered to be an agricultural nuisance (Kingsolver, 2000).

References
Andow, D., Kareiva, P., Levin, S., & Okubo, A. (1990). Spread of invading organisms. Landscape Ecology, 4(2-3), 177-188.
Baker, R. R. (1970). Bird predation as a selective pressure on the immature stages of the cabbage butterflies, pieris rapae and P. brassicae. Journal of Zoology, 162(1), 43-59.
Gilbert, N. (1984). Control of Fecundity in Pieris rapae: I. The Problem. Journal of Animal Ecology,53(2), 581-588. doi:1. Retrieved from http://www.jstor.org/stable/4536 doi:1
Jones, R. (1987). Ants, Parasitoids, and the Cabbage Butterfly Pieris rapae. Journal of Animal Ecology,56(3), 739-749. doi:1. Retrieved from http://www.jstor.org/stable/4945 doi:1
Kingsolver, J. (2000). Feeding, Growth, and the Thermal Environment of Cabbage White Caterpillars, Pieris rapae L. Physiological and Biochemical Zoology: Ecological and Evolutionary Approaches, 73(5), 621-628. doi:1. Retrieved from .
Obara, Y. (1970). Studies on the mating behavior of the white cabbage butterfly, pieris rapae crucivora boisduval. Zeitschrift Für Vergleichende Physiologie, 69(1), 99-116.
Robinson, N., Armstead, S., & Deane Bowers, M. (2012). Butterfly community ecology: The influences of habitat type, weather patterns, and dominant species in a temperate ecosystem. Entomologia Experimentalis Et Applicata,145(1), 50-61. doi:10.1111/j.1570-7458.2012.01308.x
Wiklund, C., Karlsson, B., & Leimar, O. (2001). Sexual Conflict and Cooperation in Butterfly Reproduction: A Comparative Study of Polyandry and Female Fitness. Proceedings: Biological Sciences, 268(1477), 1661-1667. Retrieved from http://www.jstor.org/stable/3068096