Papilio zelicaon

Geographic Range

Anise swallowtails (Papilio zelicaon) live throughout the western United States, from the Rocky Mountains to the Pacific Coast. More specifically, they inhabit much of Washington, Oregon, Idaho, Nevada, Utah, Wyoming, Colorado, Montana, and California, as well as the western portions of North Dakota and South Dakota. Anise swallowtail live as far south as Baja California in Mexico and as far north as British Columbia and Saskatchewan in Canada. They have also been recorded in northern Alberta. In California, large populations exist in Suisan Marsh in Solano, Rancho Cordova in Sacramento, Forest Hill and Donner Pass in Placer, and the city of Davis. (Glassberg, 2001; Layberry, et al., 1998; Shapiro and Forister, 2003; Sims, 1976)


Anise swallowtails have been found from the Pacific seashore and coastal freshwater marshes to high mountains. They live in habitats that range in elevation from 86 m below sea level to 4,400 m above sea level. Anise swallowtails are often found in undisturbed mountainous areas or lowland areas with open canopies. Male anise swallowtails are commonly found on hilltops and other high altitude resting places such as cliffs or mountain edges, or on high points of foliage in their environment. Males select these areas as part of their mating rituals. In recent years, anise swallowtails adults and caterpillars have been found in sweet orange (Citrus sinensis) orchards in California. (Glassberg, 2001; Layberry, et al., 1998; Sims, 1976; Sims, 1983)

  • Range elevation
    -86 to 5000 m
    -282.15 to 16404.20 ft

Physical Description

Anise swallowtail caterpillars are large and smooth. Their first instar is often black with white stripes or white spots. As they molt and reach later instars they change colors until, at the fifth instar, they are green with black and yellow stripes. Anise swallowtail caterpillars have orange Y-shaped glands located just behind their heads.

Adult anise swallowtails have wingspans between 52 and 80 mm. They have six legs and are covered by sensory hairs, called setae, all over the body, including their antennae. Anise swallowtails have a short black "tail" that extends from the posterior margin of each of their hindwings, giving them the appearance of having a forked tail like that of a swallow (family Hirundinidae). Anise swallowtails are predominantly yellow. They have broad yellow bands on their hindwings and forewings that extend to the base of their wings. They have bright blue spotting on the posterior portion of their hindwings along with posteromedial orange eyespots with centered black pupils. Anise swallowtails have black abdomens with lateral yellow stripes. Males and females resemble each other in size and coloration. (Debinski and Pritchard, 2002; Layberry, et al., 1998; Putnam and Putnam, 1997)

  • Sexual Dimorphism
  • sexes alike
  • Range wingspan
    52 to 80 mm
    2.05 to 3.15 in


Anise swallowtails develop through complete metamorphosis. Reproductive females lay their eggs on vegetation, or in other places with favorable conditions for egg development. Caterpillars, their larval stage, hatch from eggs and go through 5 sub-stages known as instars. During each instar, caterpillars grow larger and molt to reach their next instar. As they develop through their 5 instars, caterpillars change in coloration from black and white to green with black and orange or yellow. Once caterpillars reach their final instar, they defecate everything in their system and then begin the next stage of metamorphosis, forming a chrysalis. Chrysalises are green at first, but slowly turn brown as butterflies develop within. Adult butterflies emerge from their chrysalises and look for mates to begin a new breeding cycle.

Anise swallowtails develop from eggs to adults in 30 to 60 days. On average, males develop 1 to 2 days faster than females. Adult anise swallowtails typically live 2 to 14 days. Females generally live longer than males, though there is currently no scientific explanation supported by research. (Sims, 1976)


Anise swallowtails mate multiple times, sometimes only hours apart, and with multiple partners. Females who mate with low quality males are more likely to mate multiple times compared to females who mate with high quality males. Additionally, females that mated with low quality males tend to lay fewer eggs than females that mated with high quality males. During a successful mating event, males deposit a packet of sperm, called a spermatophore, in their mate. Females can carry more than one spermatophore at a time, each from a separate mating event. Internal fertilization can occur in females up to several hours after males deliver their spermatophore. Reproductive timing for anise swallowtails is not seasonal; they breed continuously through the duration of their adult life. (Sims, 1976)

Anise swallowtails exhibit a mating behavior known as "hill topping". Males perch on hill tops, montane cliffs, or high foliage so that females can easily find them. Females instinctively fly to these areas to search for mates. The first reproductive cycle for males and females typically occurs near the place where they emerge from their chrysalises. Male anise swallowtails can be aggressive during breeding season, defending specific territories and attacking other males while searching for potential mates. (Sims, 1976)

  • Breeding interval
    Male and female anise swallowtails mate throughout their adult life stage.
  • Breeding season
    Courtship, mating, and oviposition can occur at any point during the adult life stage of anise swallowtails.
  • Range gestation period
    1 to 3 days
  • Range time to independence
    1 to 3 days
  • Range age at sexual or reproductive maturity (female)
    20 to 23 days
  • Average age at sexual or reproductive maturity (female)
    21 days
  • Range age at sexual or reproductive maturity (male)
    20 to 23 days
  • Average age at sexual or reproductive maturity (male)
    22 days

Female anise swallowtails lay their eggs in safe locations, often on plants where newly hatched larvae have access to a food source. Females exhibit no further parental investment beyond oviposition. Males exhibit no parental investment beyond the act of mating. (Sims, 1976; Wehling and Thompson, 1997)

  • Parental Investment
  • no parental involvement
  • pre-hatching/birth
    • provisioning
      • female


Anise swallowtails have a relatively short lifespan. In total, anise swallowtails live for approximately 10 weeks in the wild. After hatching from eggs, anise swallowtails spend approximately 4 weeks as caterpillars and 4 weeks as chrysalises before becoming fully-developed adults. Adult anise swallowtails live around 2 to 14 days, although the maximum recorded lifespan of an adult was 30 days. There are no known reports of lifespans for anise swallowtails in captivity. (Sims, 1976)

  • Typical lifespan
    Status: wild
    58 to 84 days
  • Average lifespan
    Status: wild
    70 days


Adult anise swallowtails are active only during the day, whereas caterpillars are active intermittently during both day and night. Aside from breeding behaviors, anise swallowtails are solitary. For mating purposes, male anise swallowtails exhibit a behavior called "hill topping", where they perch on hill tops, mountain cliffs, or tall foliage to display themselves to females. In cases where multiple males attempt to use the same high point for their display, they engage in aggressive dances to claim the territory. When a female selects a male as a mate, the two may not copulate immediately. When this occurs, males guard females by flying aggressively at incoming males.

In some cases, anise swallowtails overwinter in their pupal phase. Studies have shown that some overwintering pupae display super cooling points at -20 °C and can tolerate short periods at temperatures as low as -30 °C. However, pupae are vulnerable to cold snaps below these temperatures, and other life phases are not as tolerant of cold conditions. Therefore, anise swallowtails are limited to certain environments due to their temperature tolerance. Some researchers have predicted that mortality rates of anise swallowtails may increase as global climate change increases the chance of cold snaps in spring throughout parts of their range.

Female anise swallowtails occasionally lay their eggs on bishop's weed (Aegopodium podagraria), an invasive plant species which has been found to be fatally toxic to anise swallowtail larvae. Scientists have concluded that anise swallowtail populations will be negatively impacted by this association. It is possible that anise swallowtails will either adapt to tolerate the chemistry of bishop's weed or learn to avoid the plant completely.

The formal collective name for a group of anise swallowtails is a kaleidoscope, though it may also be referred to as a swarm or a rabble. A group of caterpillars is called an army. (Thacker, 2004; Williams, et al., 2014)

Home Range

The home range of anise swallowtails must contain certain food sources and landscape features. They feed on host plants in the family Apiaceae. The most common and most abundant food source for anise swallowtails is sweet fennel (Foeniculum vulgare). Anise swallowtails also typically have home ranges in areas with hilltops, cliffs, or tall foliage, which are important features for male mating displays. One study reported 12 populations of anise swallowtails spanning over 1,200 km. Not much is knows about the size of territories that anise swallowtails defend, although males aggressively defend areas involved in mating displays. (Garth, 1986; Sims, 1976; Thacker, 2004; Wehling and Thompson, 1997)

Communication and Perception

There is limited information regarding communication and perception in anise swallowtails specifically. However, other species of butterflies have various ways of communicating and perceiving their environment. Butterflies use vision as a way to communicate. They are able to distinguish color patterns to recognize their own species. Certain physical movements can be used during courtship rituals or to communicate aggression between males over territory. Butterflies also use chemical signals to communicate. Male and female butterflies both produce pheromones. They use chemoreceptors on their legs, feet, antennae, and palps to "smell" the pheromones that conspecifics produce. Pheromones are the most common form of communication that butterflies use to find suitable mates. (Davies and Butler, 2008)

Food Habits

Anise swallowtail adults are nectarivores and caterpillars are folivores, feeding on plants in the carrot family (Apiaceae). Anise swallowtails most commonly use sweet fennel (Foeniculum vulgare) as a host plant. Other food sources include native plants such as water hemlock (Cicuta maculata) and water dropwort (Oenanthe javanica). In recent years, research has shown that anise swallowtail adults also feed on bishop's weed (Ammi majus), though it is toxic to caterpillars.

Anise swallowtails also use sweet orange (Citrus sinensis) as a host plant, a behavior first reported in 1981. Sweet orange was introduced to North America as a fruit crop and is the only known plant species outside of the carrot family that anise swallowtails use as hosts. Sweet orange produces chemical compounds similar to those present in members of the carrot family. Anise swallowtail caterpillars instinctively eat plants that produce such compounds, so this is likely the reason that they are attracted to sweet orange. (Berenbaum, 1990; Herman, 1981; Thacker, 2004)

  • Plant Foods
  • leaves
  • nectar


There is limited information regarding specific predators of anise swallowtails. Butterfly species often defend themselves by producing chemicals that make them unpalatable or toxic to potential predators. Many butterfly species, including anise swallowtails, have bright, aposematic coloration to warn predators of their toxicity. Other butterfly species that are non-toxic still have bright coloration to mimic the coloration of truly toxic species. Anise swallowtail caterpillars often hide in dense foliage to avoid predation, and later instars display aposematic coloration. Adults can fly to escape predators and they have coloration and physical structures on their hindwings that resemble eyespots and antennae, respectively. These features can deter predators from attacking or otherwise confuse predators into attacking non-vital parts of their bodies.

Specific predators of butterfly eggs include lady beetles (family Coccinellidae), green lacewings (family Chrysopidae), and mites (class Arachnida). Species that prey on caterpillars include ants (family Formicidae), lizards (order Squamata), and parasitic flies (family Tachinidae). Shrews (order Soricidae) and mice (order Rodentia) are known to prey on chrysalises, and frogs and toads (order Anura), spiders (order Araneae), and praying mantises (order Mantodea) prey on adult butterflies. Wasps (order Hymenoptera) and insect-eating birds (class Aves) prey on both caterpillars and adults. (Carrell, 2012; Glassberg, 2001; Layberry, et al., 1998)

Ecosystem Roles

There is limited information on the ecosystem roles specific to anise swallowtails. In general, butterfly species feed on nectar from flowers. As they move between flowers of the same plant species, they transfer pollen between individuals and thus play a role in plant reproduction. It is likely that anise swallowtails play a role in pollinating the plants on which they feed.

In contrast, caterpillars of many butterfly species can defoliate plants if their populations are large enough. Without leaves to conduct photosynthesis, affected plants may struggle to survive. In recent years, sweet orange orchards in California have been over populated by anise swallowtail caterpillars. In efforts to reduce population outbreaks, farmers and land managers have introduced parasitoid wasps in the genus Hyposoter to sweet orange plantations. These wasps lay their eggs in caterpillar larvae, so their presence acts as a natural population control for anise swallowtail outbreaks.

In addition to their roles as pollinators and herbivores, anise swallowtails serve an ecosystem role as prey for various arthropod and vertebrate species. (Carrell, 2012)

  • Ecosystem Impact
  • pollinates
Mutualist Species
  • None known at this time
Commensal/Parasitic Species

Economic Importance for Humans: Positive

There is limited information on the economic importance of anise swallowtails specifically. Many butterfly species are a source of ecotourism, with butterfly enthusiasts traveling long distances to view new species. Furthermore, butterfly gardens are a popular attraction in many cities, and it is possible that some butterfly gardens include anise swallowtails. (Carrell, 2012)

Economic Importance for Humans: Negative

Anise swallowtails have become a pest species at sweet orange (Citrus sinensis) plantations in California, with caterpillars consuming the leaves and reducing the productivity of crop plants. Land managers have begun using parasitoid wasps in the genus Hyposoter as a method of biocontrol. Furthermore, farmers have begun planting sweet fennel (Foeniculum vulgare) in rows throughout sweet orange orchards. Since this is the main host plant for anise swallowtails, it acts as a "crop trap" that reduces herbivory on sweet orange trees. (Herman, 1981; Morse, et al., 2014)

  • Negative Impacts
  • crop pest

Conservation Status

Anise swallowtails have not yet been evaluated on the IUCN Red List. They are not listed on any other national or international conservation list, and populations are considered stable throughout their range. There are no recovery plans currently in place for anise swallowtails. (Collins and Morris, 1985)


Megan Hodge (author), Radford University, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Emily Clark (editor), Radford University, Cari Mcgregor (editor), Radford University, Jacob Vaught (editor), Radford University.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


uses sound to communicate


having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

  1. active during the day, 2. lasting for one day.

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


an animal that mainly eats leaves.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


An animal that eats mainly plants or parts of plants.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


marshes are wetland areas often dominated by grasses and reeds.


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an animal that mainly eats nectar from flowers


active during the night


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


chemicals released into air or water that are detected by and responded to by other animals of the same species


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


lives alone


living in residential areas on the outskirts of large cities or towns.


uses touch to communicate


defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement


living in cities and large towns, landscapes dominated by human structures and activity.


uses sight to communicate

year-round breeding

breeding takes place throughout the year


Argue, C. 2011. The Pollination Biology of North American Orchids: Volume 1: North of Florida and Mexico. New York, NY: Springer Science and Business Media.

Berenbaum, M. 1990. Evolution of specialization in insect-umbellifer associations. Annual Reviews of Entomology, 35: 319-343.

Carrell, E. 2012. Butterflies are Forever. Bloomington, IN: Booktango.

Collins, M., M. Morris. 1985. Threatened Swallowtail Butterflies of the World: The IUCN Red Data Book. Oxford, UK: Information Press.

Davies, H., C. Butler. 2008. Do Butterflies Bite? : Fascinating Answers to Questions about Butterflies and Moths. New Brunswick, NJ, and London: Rutgers University Press.

Debinski, D., J. Pritchard. 2002. A Field Guide to Butterflies of the Greater Yellowstone Ecosystem. Lanham, MD: Rinehart Publishers.

Garth, J. 1986. California Butterflies. Berkeley, California: University of California Press.

Glassberg, J. 2001. Butterflies Through Binoculars. New York, NY: Oxford University Press.

Herman, R. 1981. New Scientist. New York, NY: Reed Business Information.

Layberry, R., P. Hall, D. Lafontaine. 1998. The Butterflies of Canada. Canada: University of Toronto Press.

Morse, J., E. Crafton-Cardwell, N. O'Connell, P. Phillips, C. Kallser, D. Haviland. 2014. "California Orangedog" (On-line). Accessed March 26, 2015 at

Putnam, P., M. Putnam. 1997. North Americas Favorite Butterflies: A Pictorial Guide. Minocqua, WI: Willow Creek Press.

Rose, M. 1998. Darwin's Spectre: Evolutionary Biology Modern World. Princeton, NJ: Princeton University Press.

Shapiro, A., M. Forister. 2003. Wing pattern variation in the anise swallowtail, Papilio zelicaon (Lepidoptera: Papilionidae). Annals of the Entomologist Society of America, 96/1: 73-80.

Sims, S. 1976. Aspects of mating frequency and reproductive maturity in Papilio zelicaon. American Midland Naturalist, 102/1: 36-50.

Sims, S. 1983. The genetic and environmental basis of pupal colour dimorphism in Papilio zelicaon (Lepidoptera: Papilionidae). Heredity, 50/2: 159-168.

Sims, S. 1980. Diapause dynamics and host plant suitability of Papilio zelicaon (Lepidoptera: Papilionidae). American Midland Naturalist, 103/2: 375-384.

Thacker, P. 2004. California butterflies: At home with aliens. Bioscience, 54/3: 182-187.

Wehling, W., J. Thompson. 1997. Evolutionary conservation of oviposition preference in a widespread polyphagous insect herbivore, Papilio zelicaon. Oecologia, 111/2: 209-215.

Williams, C., A. Nicolai, L. Ferguson, M. Bernards, J. Hellman, B. Sinclair. 2014. Cold hardiness and deacclimation of overwintering Papilio zelicaon pupae. Comparative Biochemisry and Physiology Part A: Molecular and Integrative Physiology, 178: 51-58.