are yellow brown instead of tawny orange and the white spots are larger.[24] The shape and color of the wings change at the beginning of the migration and appear redder and more elongated than later migrants.[25] Wings size and shape differ between migratory and non-migratory monarchs. Monarchs from eastern North America have larger and more angular forewings than those in the western population.[10] Monarch flight has been described as "slow and sailing".[26] Monarch flight speed has been estimated by a number of researchers. One scientist examined all prior estimates and concluded their flight speed is approximately 9 km/h or 5.5 mph.[27] For comparison, the average human jogs at a rate of 9.7–12.9 km/h (6–8 mph).

Adults are sexually dimorphic. Males are slightly larger than females[10][24] and have a black patch or spot of androconial scales on each hindwing (in some butterflies, these patches disperse pheromones, but are not known to do so in monarchs). The male's black wing veins are lighter and narrower than those of females.[28]

One variation, the "white monarch", observed in Australia, New Zealand, Indonesia and the United States, is called nivosus by lepidopterists. It is grayish white in all areas of its wings that are normally orange and is only about 1% or less of all monarchs, but populations as high as 10% exist on Oahu in Hawaii.[17]

The monarch has six legs like all insects, but uses only its middle legs and hindlegs as the forelegs are vestigial, as in all Nymphalidae, and held against its body.[29]

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tour dates

The monarch butterfly or simply monarch (Danaus plexippus) is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae.[4] Other common names depending on region include milkweed, common tiger, wanderer, and black veined brown.[5] It may be the most familiar North American butterfly, and is considered an iconic pollinator species.[6] Its wings feature an easily recognizable black, orange, and white pattern, with a wingspan of 8.9–10.2 cm (​3 1⁄2–4 in)[7] A Müllerian mimic, the viceroy butterfly is similar in color and pattern, but is markedly smaller and has an extra black stripe across each hindwing.

The eastern North American monarch population is notable for its annual southward late-summer/autumn migration from the northern and central United States and southern Canada to Florida and Mexico.[4] During the fall migration, monarchs cover thousands of miles, with a corresponding multi-generational return north. The western North American population of monarchs west of the Rocky Mountains often migrates to sites in southern California but has been found in overwintering Mexican sites as well.[8][9] Monarchs have been bred on the International Space Station.[10]

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fan base

Commonly and easily mistaken for the similar viceroy butterfly – the two species are Müllerian mimics, the monarch's wingspan ranges from 8.9 to 10.2 centimetres (3.5–4.0 in).[7] The uppersides of the wings are tawny orange, the veins and margins are black, and there are two series of small white spots in the margins. Monarch forewings also have a few orange spots near their tips. Wing undersides are similar, but the tips of forewings and hindwings are yellow brown instead of tawny orange and the white spots are larger.[24] The shape and color of the wings change at the beginning of the migration and appear redder and more elongated than later migrants.[25] Wings size and shape differ between migratory and non-migratory monarchs. Monarchs from eastern North America have larger and more angular forewings than those in the western population.[10]

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Monarch flight has been described as "slow and sailing".[26] Monarch flight speed has been estimated by a number of researchers. One scientist examined all prior estimates and concluded their flight speed is approximately 9 km/h or 5.5 mph.[27] For comparison, the average human jogs at a rate of 9.7–12.9 km/h (6–8 mph).

Adults are sexually dimorphic. Males are slightly larger than females[10][24] and have a black patch or spot of androconial scales on each hindwing (in some butterflies, these patches disperse pheromones, but are not known to do so in monarchs). The male's black wing veins are lighter and narrower than those of females.[28]

One variation, the "white monarch", observed in Australia, New Zealand, Indonesia and the United States, is called nivosus by lepidopterists. It is grayish white in all areas of its wings that are normally orange and is only about 1% or less of all monarchs, but populations as high as 10% exist on Oahu in Hawaii.[17]

The monarch has six legs like all insects, but uses only its middle legs and hindlegs as the forelegs are vestigial, as in all Nymphalidae, and held against its body.[29]

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conservation efforts

Many of the priority projects that the national strategy identifies will focus on the I-35 corridor extending for 1,500 miles (2,400 km) from Texas to Minnesota that provides spring and summer breeding habitats in the monarch's key migration corridor.[164]There have been a number of national and local efforts underway to establish pollinator habitat along highways and roadways, although this effort is controversial. Conservationists are lobbying transportation departments and utilities to reduce their use of herbicides and specifically encourage milkweed to grow along roadways and power lines.
 

Reducing roadside mowing and application of herbicides during the butterfly breeding season will encourage milkweed growth.[165] Conservationists lobby agriculture companies to set aside areas that remain unsprayed to allow the butterflies to breed.[132] This practice is controversial because of the high risk of butterfly mortality near roads, as several studies have shown that millions of monarchs and other butterflies are killed by cars every year [139] There is also evidence that monarch larvae living near roads experience physiological stress conditions, as evidenced by elevations in their heart rate.[166]

A 2020 resource from the Cooperative Research Programs of the Transportation Research Board developed products for roadway corridors to provide habitat for monarch butterflies and developed tools for roadside managers to optimize potential habitat for monarch butterflies in their road right-of-ways. [167]

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discography

There is increasing concern related to the ongoing decline of monarchs at their overwintering sites; based on a 2014 twenty-year comparison, the overwintering numbers west of the Rocky Mountains have dropped more than 50 percent since 1997 and the overwintering numbers east of the Rockies have declined by more than 90 percent since 1995.[10]

In February 2015, the U.S. Fish and Wildlife Service provided a statistic showing that nearly a billion monarchs have vanished from the overwintering sites since 1990. At that time, one of the main reasons cited was the herbicides used by farmers and homeowners on milkweed, a plant used as a food source, a home and a nursery by the monarchs.[129] A 2016 study also attributed the last decade's ten-fold decline in overwintering numbers of the eastern monarch population to the loss of breeding habitat, namely the many species of milkweed (Asclepias species) that developing larvae require for food; however, scientists believe there are other factors as well.

A number of researchers believe milkweed loss during the breeding season is the cause because declines in milkweed abundance are highly correlated with the adoption of herbicide-tolerant genetically modified corn and soybeans, which now constitute 89% and 94% of these crops, respectively, in the U.S.[122] However, correlative evidence does not prove causation, and other possible causes of the overwintering declines have been proposed. A 2018 study has suggested that the decline in milkweed predates the arrival of GM crops.[130]

This page was last edited on 3 March 2020, at 03:48 (UTC).

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