Pontia protodice

Geographic Range

Known as the southern cabbageworm in its larval stage, Pontia protodice , the checkered white butterfly, is commonly found across the United States into northern Mexico. Temporary populations occur as the adults move North, with some populations appearing in southern Canada. These are often seasonal populations which fall South again in fall and winter. The species does not occur in the Pacific Northwest nor the majority of New England, with highly erratic populations east of the Appalachians.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Checkered whites are found mainly in open, dry or sandy disturbed habitats and are not found in forested or shady areas. They commonly thrive in tundras, grasslands, deserts and steppes, and inhabit roadsides, railroad beds, empty or sandy lots, beach dunes, fields and pastures. Although they have been reported from 76 m to 3764 m in elevation, checkered whites are most common below 3048 m, and typically reproduce below 2743 m.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• tundra tundra
• desert or dune desert or dune
• savanna or grassland savanna or grassland
• mountains mountains

• Other Habitat Features
• suburban suburban
• agricultural agricultural

Physical Description

Southern cabbageworms grow up to 3.5 cm and have 4 long yellow stripes with gray to gray-blue coloration between. Their bodies are dotted with numerous black spots from which small hairs, called setae, protrude. Males and females can be differentiated as males have immaculate hind wings and forewings with 1 to 3 black marks. Females are much more heavily patterned, with up to 50 percent of their forewings and the outer margins of their hind wings covered in black marks. Checkered whites can also take on slight variations to their patterns when they emerge in the summer versus the spring and fall. Spring or fall butterflies, the short-day form, get less sunlight during their development which creates more distinct green-gray veins on the ventral side of their wings and lighter patterns than the long-day form. Checkered whites have a wingspan between 3.5 to 6.3 cm, the males being slightly smaller than the females and the short-day form being slightly smaller on average. Visually similar to Pieris rapae .

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently

Development

Eggs of P. protodice are barrel-shaped with deep ridges. They begin yellow and turn orange as they mature. The eggs are usually laid singly on the flowers or stems of host plants. Larvae hatch after 4 to 7 days and transition through five instars and four molts before pupating after an average of 15 to 16 days. The chrysalids are green or brown with black spotting and yellow-white angular lines on small ridges. The adults emerge after 10 to 15 days, except for the late season generations, which overwinter as pupae. Males often emerge earlier than females and adults typically live up to 10 days. Pupae resemble those of Pieris rapae .

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

Male checkered whites emerge before the females and begin patrol flights in search of mates. Courtship takes about 3 seconds before mating ensues, and males regularly lead females on post-nuptial flights to avoid competition from other males. On these flights, males transfer a spermatophore to the female. Checkered whites are known to produce about 50 eggs each time they mate, and females have the potential to mate more than once. This process usually happens the day of emergence for the females, but females will migrate if local populations are dense. New females or those with small spermatophores have been observed fluttering around males to encourage courtship and mating. Short-day form butterflies typically have lower fitness levels, and may not produce as many eggs.

• Mating System
• polyandrous polyandrous

Sexual maturity is reached upon emergence from the chrysalis for both males and females. Females lay around 50 eggs each, and solitary larvae hatch approximately 3 days later. There is no parental care.

• Key Reproductive Features
• semelparous semelparous
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous
• sperm-storing sperm-storing

Checkered whites do not provide care for their offspring.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Checkered whites live approximately 30 days, 3 to 5 are spent in eggs, 14 to 16 days are spent in the larval stage, 10 to 14 days are spent as pupae and 6 to 10 days as adults. Short-day form butterflies typically have shorter lives, and late broods overwinter as pupae.

Behavior

Pontia protodice are solitary, beginning with eggs laid singly. They have 3 flights per year with a 4th partial flight as late as November. This butterfly can reach high elevations and northern regions, though populations at these locations are often non-breeding or erratic and migratory. Checkered whites are day active.

• Key Behaviors
• flies
• diurnal diurnal
• solitary solitary

Communication and Perception

Like most butterflies, checkered whites respond to visual stimuli through compound eyes. They do not, however, rely on coloration or patterns to communicate. Instead, sexes identify one another through UV reflectivity.

• Communication Channels
• visual visual
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• ultraviolet
• chemical chemical

Food Habits

Eggs are laid on larval host plants, which include mostly mustards in Brassicaceae . Many plants the southern cabbageworms consume are crop species, including cabbage, broccoli, cauliflower, turnips and radishes. The larva prefer to consume flowers and buds, but will eat leaves. On cabbage they tend to prefer the outer leaves. Adults are nectar feeders, and have been know to feed from over 50 species of plants.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• nectar
• flowers

Predation

Known predators include robber flies ( Proctacanthus milbertii ) and robins ( Turdus migratorius ) and introduced parasitoid flies. Additionally, the introduced biocontrol agent Costesia glomerata , intended to control P. rapae , preys upon P. protodice . Other predators may include assassin bugs as well as other parasitoids and birds.

• Anti-predator Adaptations
• aposematic aposematic

Ecosystem Roles

Southern cabbageworms, the larvae, play a role as a minor agricultural pest. They often feed on cabbage, cauliflower, broccoli, radishes and turnips. However, they also feed on wild mustards, and have been largely replaced as a pest by the imported cabbageworm. Additionally, southern cabbageworms tend to feed on outer leaves of crops such as cabbage and broccoli, and are therefore less harmful to crops than P. rapae . The adults, checkered whites, are solely nectar feeders and may play a role in pollination based on the habits of similar species.

Economic Importance for Humans: Positive

Checkered whites may be pollinators based on similar species including P. rapae . However, there is not enough literature on the subject.

• Positive Impacts
• pollinates crops

Economic Importance for Humans: Negative

Southern cabbageworms are considered a minor agricultural pest.

• Negative Impacts
• crop pest

Conservation Status

Checkered whites have seen a population decline, with a heightened rate since the release of biocontrol agent C. glomerata targeted at P. rapae . Other reasons for decline include pesticides and herbicides, habitat loss and fragmentation, development, light-pollution, over-grazing, land clearing, erosion, sea-level rise and irregular fire seasons. There is little conservation action currently, howver, checkered whites have been identified as a second-priority species vulnerable to climate change by the New York State Department of Environmental Conservation and The Nature Conservancy.

Additional Links

Encyclopedia of Life

Contributors

Claire Walther (author), Special Projects, Amy Bagby (), Colorado State University.

References

Capinera, J. 2001. Handbook of Vegetable Pests . New York: Academic Press.

Hall, D. 2015. "southern cabbageworm (larva), checkered white (adult) scientific name: Pontia (Pieris) protodice (Boisduval & Leconte) (Insecta: Lepidoptera: Pieridae: Pierinae)" (On-line). Featured Creatures - Entomology and Nematology. Accessed July 15, 2021 at https://entnemdept.ufl.edu/creatures/veg/leaf/checkered_white.htm .

Opler, P., G. Krizek. 1984. Butterflies East of the Great Plains . Baltimore, Maryland: The Johns Hopkins University Press.

Shapiro, A. 1992. Twenty Years of Fluctuating Parapatry and the Question of Competitive Exclusion in the Butterflies Pontia Occidentalis and P. Protodice (Lepidoptera: Pieridae). Journal of the New York Entomological Society , vol. 100, no. 2: 311-319. Accessed July 15, 2021 at www.jstor.org/stable/25009966 .

Wagner, D. 2005. Caterpillars of Eastern North America . New Jersey: Princeton University Press.

Metalmark Web and Data. 2021. "Checkered White" (On-line). Butterflies and Moths of North America. Accessed July 14, 2021 at https://www.butterfliesandmoths.org/species/Pontia-protodice .

Montana Natural Heritage Program. 2021. "Montana Field Guide" (On-line). Checkered white - Pontia protodice. Accessed July 15, 2021 at https://fieldguide.mt.gov/speciesDetail.aspx?elcode=IILEPA1030 .

2020. "Pontia protodice (Checkered White)" (On-line). World Species. Accessed July 16, 2021 at https://worldspecies.org/ntaxa/713343#predator .

New York State Department of Environmental Conservation. Species Assessment for Checkered white Butterfly. Section 182.2(i) of 6NYCRR Part 182. New York: New York State Department of Environmental Conservation. 2014. Accessed July 14, 2021 at https://www.dec.ny.gov/docs/wildlife_pdf/sgcncheckwhite.pdf .