Rocky Mountain parnassian

Naming

''P. smintheus'' has the following subspecies:
⤷ ''P. s. magnus'' Wright, 1905: Washington State
⤷ ''P. s. olympiannus'' Burdick, 1941: Olympic Mountains, Vancouver Island
⤷ ''P. s. pseudorotgeri'' Eisner, 1966: Colorado
⤷ ''P. s. sayii'' Edwards, 1863
⤷ ''P. s. smintheus'' Doubleday, 1847
⤷ ''P. s. sternitzkyi'' McDunnough, 1936: North California
⤷ ''P. s. xanthus'' Ehrmann, 1918: Washington State
⤷ ''P. s. yukonensis'' Eisner, 1969: South Yukon, British Columbia''P. smintheus'' is often misidentified as ''Parnassius phoebus'', which is a closely related Holarctic species. Some researchers also tend to split the North American population of the butterfly into two or three species. Usually, the northernmost populations will be regarded as being part of ''P. phoebus,'' while the rest is considered to be ''P. smintheus''. These regional species can be best distinguished by the location of where they are found.

⤷  ''P. phoebus''
⤷  ''P. clodius''
⤷  ''P. eversmanni''

Status

''P. smintheus'' is currently abundant in the Rocky Mountains, but the closely related species ''Parnassius apollo'' and ''Parnassius mnemosyne'' are threatened in Europe due to habitat loss and population isolation. These phenomena are beginning to endanger ''P. smintheus'' as well. Due to fire suppression and possibly global warming, the tree line has risen while the meadow areas have decreased by over 78% since 1952. There is likely to be less feeding grounds for the larvae of this species as the tree line continues to rise, since they prefer to feed further away from it. Conservation efforts would best be directed at conserving remaining habitat and promoting connectivity among existing populations. Connectivity may be maintained by preventing forest encroachment and maintaining unforested corridors among patches.

''Parnassius smintheus'' is vulnerable to changes in temperature as a result of climate change. In particular, warm Novembers as well as short-term cold and warm temperatures extremes in November are associated with the greatest declines in population. Short term warm weather in November could cause premature hatching of the eggs, the larvae of which would then die as normal winter temperatures resume.

Behavior

Males of this species often have poor visual discrimination, so they investigate all flying or sitting objects of the approximate size and color of the females of their species. They primarily identify females by their light color, so they are as likely to chase small blue lycaenids as they are to chase large white butterflies, but tend to ignore darker butterflies like fritillaries. The males emerge from their pupae before females do in order to patrol for newly emerged females over a large area. They patrol by flying over large areas then investigating any resting or flying females after spotting them. Males fly long distances continuously in search of females, stopping only to bask or feed.The species has no courtship. Rather, males simply dive on a female upon finding her and force her down to the ground if she is not already there, and forcibly attempt to mate. This is successful if she has not already mated, but usually unsuccessful if she has already mated, due to a mating plug, a small waxy plug deposited onto a female's abdomen by a male to prevent future copulation. Unsuccessful matings may last an hour or more before the female escapes. If a female is unreceptive to mating, she may close up her wings tightly when a male approaches in an attempt to avoid being seen.

Habitat

The range of the butterfly is based primarily in the Rocky Mountains, which spans Canada and the United States. This includes the mountainous areas of Yukon, Alaska, and British Columbia in Canada, and as far south as New Mexico in the United States.

''P. smintheus'' can often be found in alpine and subalpine meadows. It was found that males of this species preferred meadows with a greater abundance of nectar flowers and a higher quantity of the host plant ''Sedum lanceolatum''. They also preferred meadows with a greater number of females of their species. Males may sample two or more meadows to gain information on their relative quality. It has been suggested that this preference in males for meadows with more food resources may be due to their increased energy requirements, as they spend much more time flying than females. In contrast, the female butterflies showed no preference for meadows with more nectar flowers or host plants, or for greater numbers of males.

Reproduction

The larva completes five instars before pupating, developing over a period of around 10 to 12 weeks. The first instar larva has a black body with many hairs, and a dull black head. As the larva feeds on its host plant ''S. lanceolatum'', it sequesters in its body sarmentosin from the plant, causing the larva to become distasteful to predators. Conspicuous yellow markings appear on the body after the second instar, warning off predators, as the larva stores higher levels of sarmentosin. The fifth instar larva is black, with many short fine black hairs littered over its body. It sports two lateral and two dorsal rows of bright yellow spots. It has small and pale yellow vestigial osmeteria, a special organ just behind the head that resemble feelers. Since they may not always hatch close to their foodplant, the larvae have a fast, directional search pattern. They tend to feed rapidly on their larval host plant, then move to a basking location on open ground up to a few meters away for thermoregulation. If disturbed, the larvae twitch violently, then drop to the ground to seek cover, and may discharge a bad-smelling brown chemical.

Food

The primary larval host plant is ''Sedum lanceolatum'', spearleaf stonecrop, a yellow-flowered perennial succulent common in rocky habitats in Western North America. Larval foodplants may less frequently include other stonecrop species, including ''S. divergens, S. oreganum, S. stenopetalum,'' and ''S. integrifolium''. The foodplants tend to grow most abundantly on steep, well-drained, gravelly slopes. They can mostly be found 20–40 meters above the tree-line. Herbivores rarely feedon ''S. lanceolatum'', because it produces a deterrent cyanoglycoside, sarmentosin, so there is little risk that larvae will be accidentally preyed upon as a result of the foodplant being ingested.

The larvae also sequester sarmentosin from the plant in their bodies for their own defense. However, it has been found that if the ''S. lanceolatum'' plant becomes physically damaged by mechanical means, the larvae feeding on it have reduced growth rates, possibly due to an induced defense by the plant itself. While damage by insects does not cause plant defense, damage from feeding by the larvae does induce defense by the plant. Consequently, the larvae often hurry to feed, then switch to another host plant within the time window offering the highest nutritional quality. Larvae will typically feed and leave a plant in less than half an hour. From November to February, the leaves of their foodplant are fatally toxic to the larvae, but for the rest of the year, the larvae feed and develop normally. If the snow melts before March, the eggs hatch while the larval foodplant is still toxic, and the larvae perish.

Predators

The species faces predation in all life stages. The eggs largely face mortality by mammalian herbivores feeding on the host plant. The population on Dividend Mountain near Penticton, British Columbia, is about half the size that habitat is capable of supporting due to cattle that graze the area after oviposition has occurred. Birds are the most important predators of larvae and adult butterflies, as well as small mammals such as mice, chipmunks, and squirrels. Chipmunks will carry butterflies back to their feeding stations then chip the wings off to eat the body. Orb-weaving spiders are significant predators of adult butterflies, as are a variety of other insect predators. Ants are "partial predators" of adults, as the ants will cut away the margins of the wings for food while the butterflies are resting.