Mustard white
Pieris oleracea, or more commonly known as the mustard white, is a butterfly in the family Pieridae native to a large part of Canada and the northeastern United States. The nearly all-white butterfly is often found in wooded areas or open plains. There are two seasonal forms, which make it distinct from other similar species. Because of climate change, populations are moving further north.
As indicated by the common name, P. oleracea adults and larvae primarily feed on plants in the mustard family, Brassicaceae. The species is threatened by the rapid, and monoculture-forming, spread of the invasive species Alliaria petiolata, which is toxic to larvae. Populations of P. oleracea have been declining. It may be that this butterfly is slowly adapting to garlic mustard. However, it may not be a fast enough process to ensure its survival, due to the high level of aggression on the part of the plant and the continuing encroachment of human development.
Its specific name oleracea means "related to vegetables/herbs" in Latin and is a form of holeraceus (oleraceus).
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withPieris oleracea larvae are yellow and shaped like cones, with vertical ridges. Larvae that are mature have many black spots with a green body, dark dorsal stripe, and short, dense hairs. The pupae can range in color from brown to white to green, and have dorsal and apical projections.
There are two seasonal forms of the butterfly, one for spring and one for summer. Above the wings, the butterfly is entirely white, which a small patch of black scales at the tips of the wings. A feature that differentiates this species from other similar species is the green or yellow markings on the underside of the hind wings that run along the veins. In the spring, the green markings are very apparent, and can be seen from the top side of the wing. In the summer, the wing appears almost entirely white, as the markings on the underside of the wing and the black tips are fainter.
This species is mainly found throughout Canada and parts of the northeastern United States. They are often found with other very similar species in specific areas. Their range stretches across Canada starting from Newfoundland to Alberta and other Northwestern Territories. However, they are only found in the foothill regions of Alberta. In British Columbia, populations are found in north and central regions. In Nunavut, they are specifically found near the coast at Coppermine and Arviat. In the Cypress Hills of Saskatchewan, there is a single population that has been found. As for the United States, they are found in the New England states and Great Lakes area.
These butterflies are found in prairies, near streams, and in moist deciduous areas. In the spring, they are found more readily in the moist areas, either the woodlands or open fields.
Pieris oleracea is a biovoltine species, meaning it tends to have two broods seasonally. The time in which they fly can depend on the area the inhabit. Usually, the butterflies migrate once in June, and once again in late July. However, in southern Ontario, there can be three to four generations, and farther up north it has been observed where there is only one generation.
Because of changing climate conditions, broods are expanding farther north.
There has been a steady decline in the populations of P. oleracea, which is being attributed to either climate change, the expansion of the toxic garlic mustard plant, human development, or, most likely, a combination of these factors.
During the day, males observe the population to look for females to mate with.
A specific case of sympatry between P. oleracea and P. rapae was seen in Vermont. Even though the populations had approximately the same territory, each species was able to find a specific niche in the food source or habitat that the other could not use. P. oleracea larvae primarily used Dentaria diphylla during the spring, whereas P. rapae used Barbaea vulgaris in the spring. As for mating, there was no observed interference between the two species. Even though adults were in the same areas, there was no conflict.
