Colias

Clouded yellows
	Colias hyale – type species for the genus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Lepidoptera
Family:	Pieridae
Tribe:	Coliadini
Genus:	Colias; Fabricius, 1807
Type species
	Papilio hyale; Linnaeus, 1758
Synonyms
	Eurymus Horsfield, [1829]; Ganura Zetterstedt, [1839]; Scalidoneura Butler, 1871; Eriocolias Watson, 1895; Coliastes Hemming, 1931; Protocolias Petersen, 1963 ; Mesocolias Petersen, 1963; Neocolias Berger, 1986 ; Palaeocolias Berger, 1986; Eucolias Berger, 1986; Similicolias Berger, 1986; Paracolias Berger, 1986;

Colias is a genus of butterflies in the family Pieridae. They are often called clouded yellows in the Palearctic and sulphurs (a name also used for other coliadine genera) in North America. The closest living relative is the genus Zerene,^[4] which is sometimes included in Colias.

This genus occurs throughout the Holarctic, including the arctic regions. They are also found in South America, Africa, China and India. Their caterpillars feed on certain Fabaceae, for example vetches (Vicia). The adults forage for nectar.^[5] most are thus beneficial by keeping weeds at bay, some occasionally become nuisance pests on crops like alfalfa. In some species, the wings of males have brilliant ultraviolet reflection, while those of females do not.^[6]^[7] Adults of both sexes have various colour forms. Males are particularly conservative based off of their genitalia structures. These structures are difficult to identify making it difficult to classify the Colias.^[8]

Most if not all species of this genus, as usual for Coliadinae, do not sequester toxins or other noxious compounds from their food plants. They are therefore a well-loved prey item of insectivores as compared to Pieris of the related Pierinae. They make up this disadvantage by being more nimble and better able to evade attacks by would-be predators.^[9]

Notable lepidopterologists who did many studies on this genus included Julius Röber, J. Malcolm Fawcett, George B. Johnson and Henry Rowland-Brown.

Systematics

Hybridization runs rampant in these polytypic and clinal^[10] butterflies, confounding molecular phylogenetics studies. In general, cladistic analyses of only one type of data (particularly mtDNA sequences) cannot be considered reliable. Regardless, the evolutionary distance within some "species" is so large that cryptic speciation rather than (or in addition to) interbreeding seems to be the cause. For example, the Beringian populations traditionally assigned to the northern clouded yellow (C. hecla) could warrant recognition as a species; hybridization between North American and Asian populations seems to have played a role in their evolution, but as a whole they appear to be a rather old and distinct lineage.^[11]

Thermoregulation

Colias are behavioral thermoregulators. They will move their habitats in order to regulate their body temperature. This leads to them having specific and narrow temperature ranges that they could live in. This leaves the Colias to be extremely vulnerable to climate change.^[12] The degree of melanism on their wings and fur thickness are major parts of their thermoregulation. The wing absorption/melanization is determined by the proportions of their coloration. They are in a class of pollinators that require minimum fuel due to their small size.^[13] When they need pollen they are attracted to flower patterns in the ultraviolet, similar to themselves.

Flight

Colias spend most of their time in active flight and are very strong flyers. Flying is essential for them mate as well as pollinate. But they are very susceptible to temperature and have flight restrictions based on their body temperature. Flight activity is restricted between 27-40 degrees Celsius. Their flight performance is best once at 33-38 degrees Celsius. In order to maintain these temperatures the Colias will use a lateral basking posture. When they reach a temperature outside of the flight activity zone, Colias will find a shaded area under plants in order to cool down.^[14]

Species

The genus Colias has approximately 90 different species. It is often difficult to find differences between the species, since they are mostly identified through their wing structure and pattern.^[15]

Species

Listed alphabetically:^[16]

Colias adelaidae Verhulst, 1991
Colias aegidii Verhulst, 1990
Colias alfacariensis Ribbe, 1905 – Berger's clouded yellow
Colias alexandra W. H. Edwards, 1863 – Queen Alexandra's sulphur, Alexandra sulfur, or ultraviolet sulfur
Colias alpherakii Staudinger, 1882
Colias aquilonaris Grum-Grshimailo, 1899
Colias arida Alphéraky, 1889
Colias audre (Hemming, 1933)
Colias aurorina Herrich-Schäffer, 1850 – Greek clouded butterfly or dawn clouded yellow
Colias baeckeri Kotzsch, 1930
Colias behrii W. H. Edwards, 1866 – Behr's sulphur or Sierra green sulfur
Colias berylla Fawcett, 1904 – Everest clouded yellow
Colias canadensis Ferris, 1982 – Canada sulphur
Colias caucasica Staudinger, 1871 – Balkan clouded yellow
Colias chippewa W. H. Edwards, 1872 – heath sulphur
Colias chlorocoma Christoph, 1888
Colias christina W. H. Edwards, 1863 – Christina sulphur
Colias christophi Grum-Grshimailo, 1885
Colias chrysotheme (Esper, 1781) – lesser clouded yellow
Colias cocandica Erschoff, 1874
Colias croceus (Geoffroy, 1785) – dark clouded yellow or common clouded yellow
Colias dimera Doubleday, 1847 – dimera sulphur
Colias diva Grum-Grshimailo, 1891
Colias dubia Fawcett, 1906 – dwarf clouded yellow
Colias electo (Linnaeus, 1763) – African clouded yellow
Colias elegans Schultz, 1904
Colias elis Strecker, 1885 (often included in C. meadii; paraphyletic?)
Colias eogene C. & R. Felder, 1865 – fiery clouded yellow
Colias erate (Esper, 1805) – eastern pale clouded yellow
Colias erschoffi Alphéraky, 1881
Colias eurytheme Boisduval, 1852 – orange sulphur, alfalfa butterfly
Colias euxanthe C. & R. Felder, 1865 – Puno clouded yellow
Colias felderi Grum-Grshimailo, 1891
Colias fieldii Ménétriés, 1855

Colias flaveola Blanchard, 1852 – flaveola clouded yellow
Colias gigantea Strecker, 1900 – great (northern) sulphur
Colias grumi Alpheraky, 1897
Colias harfordii W. H. Edwards, 1877 – Harford's sulphur
Colias hecla Lefèbvre, 1836 – northern clouded yellow, Greenland sulphur, or hecla sulphur (paraphyletic?)
Colias heos (Herbst, 1792)
Colias hofmannorum Eckweiler, 2000
Colias hyale (Linnaeus, 1758) – pale clouded yellow
Colias hyperborea Grum-Grshimailo, 1899
Colias interior Scudder, 1862 – pink-edged sulphur
Colias johanseni Troubridge & Philip, 1990 – Johansen's sulphur
Colias krauthii Klots, 1935
Colias lada Grum-Grshimailo, 1891
Colias ladakensis Felder & Felder, 1865 – Ladakh clouded yellow
Colias leechi Grum-Grshimailio, 1893
Colias lesbia (Fabricius, 1775) – Lesbia clouded yellow
Colias libanotica Lederer, 1858 (sometimes included in C. aurorina)
Colias marcopolo Grum-Grshimailo, 1888
Colias marnoana Rogenhofer, 1884
Colias meadii W. H. Edwards, 1871 – Mead's sulphur
Colias montium Oberthür, 1886
Colias mukana Berger, 1981
Colias myrmidone (Esper, 1781) – Danube clouded yellow
Colias nastes Boisduval, 1834 – Labrador sulphur
Colias nebulosa Oberthür, 1894
Colias nilagiriensis Felder, C & R Felder, 1859
Colias nina Fawcett, 1904 – Fawcett's clouded yellow
Colias occidentalis Scudder, 1862 – western sulphur or golden sulfur
Colias palaeno (Linnaeus, 1761) – moorland clouded yellow, Arctic sulphur, palaeno sulphur or pale Arctic clouded yellow
Colias pelidne Boisduval & Le Conte, 1829 – blueberry sulphur or pelidne sulphur
Colias phicomone (Esper, 1780) – mountain clouded yellow
Colias philodice Godart, 1819 – common sulphur, clouded sulphur
Colias ponteni Wallengren, 1860
Colias pseudochristina Ferris, 1989
Colias regia Grum-Grshimailo, 1887
Colias romanovi Grum-Grshimailo, 1885
Colias sagartia Lederer, 1869
Colias scudderii Reakirt, 1865 – willow sulphur
Colias shahfuladi Clench & Shoumatoff, 1956
Colias sieversi Grum-Grshimailo, 1887
Colias sifanica Grum-Grshimailo, 1891
Colias staudingeri Alphéraky, 1881
Colias stoliczkana Moore, 1882 – orange clouded yellow
Colias tamerlana Staudinger, 1897
Colias thisoa Ménétriés, 1832
Colias thrasibulus Fruhstorfer, 1908 – lemon clouded yellow
Colias thula Hovanitz, 1955 – Thula sulphur
Colias tibetana Riley, 1922
Colias tyche (Böber, 1812) – pale Arctic clouded yellow, Arctic green sulphur, or Booth's sulphur
Colias viluiensis (Ménétriés, 1859)
Colias wanda Grum-Grshimaïlo, 1907
Colias wiskotti Staudinger, 1882

Distinguishing characteristics

Colias are usually some shade of yellow, orange or white. Their uppersides feature black borders (usually solid in males, often with pale spots in females). They always perch with wings closed, but upperside pattern may be seen faintly through the wing, or glimpsed in flight.^[17]