Vanessa atalanta, the red admiral or previously, the red admirable,is a well-characterized, medium-sized butterfly with black wings, orange bands, and white spots. It has a wingspan of about 2 inches. The red admiral is widely distributed across temperate regions of North Africa, the Americas, Europe, Asia, the Caribbean, and New Zealand.  It resides in warmer areas, but migrates north in spring and sometimes again in autumn. Typically found in moist woodlands, the red admiral’s primary host plant is the stinging nettle, Urtica dioica. It can also be found on the false nettle, Boehmeria cylindrica.The caterpillar feeds on nettles, and the adult drinks from flowering plants like the Buddleia and overripe fruit. Red admirals are territorial butterflies; females will only mate with males that hold territory. Males with superior flight abilities are more likely to successfully court females.
The red admiral is found in temperate regions of North Africa, North and Central America, Europe, Asia, and island regions of Hawaii, the Caribbean, and New Zealand.
In northern Europe, it is one of the last butterflies to be seen before winter sets in, often feeding on the flowers of ivy on sunny days. The red admiral is also known to hibernate, re-emerging individuals showing prominently darker colorings than the first-brood. The butterfly also flies on sunny winter days, especially in southern Europe.
In North America, the red admiral generally has two broods from March through October. Most of North America must be recolonized each spring by southern migrants, but this species over-winters in south Texas.
Male red admirals are territorial and perch during the afternoon until sunset. Larger territories are optimal and subject to increased intrusion by other males more frequently than smaller territories. Territories tend to be oval in shape, 8-24 feet long, and 13-42 feet wide. Males patrol their territory by flying around the perimeter between 7 and 30 times per hour. On average, territory holders interact with intruders 10 to 15 times per hour. 
When another male encroaches on a red admiral’s territory, the resident chases away the intruder, often in a vertical, helical path to disorient or tire out the intruder while minimizing the horizontal distance it travels from its perch. The red admiral immediately returns to its territory after chasing off encroaching males. Time spent patrolling increases as number of intruder interactions increases.
Patrolling behavior is correlated with warmer ambient temperatures, so males begin patrolling early and continue later on warmer days. Overcast skies usually led to patrolling later in the day. It is not clear whether this later start time is due to lower ambient temperature or a direct effect of decreased solar radiation. Another theory is that males believe it is earlier in the morning on cloudy days because of the reduced solar radiation. 
Larval and pupal stagesEdit
Red admiral larvae measure approximately 1 inch in length. Their coloration is variable, but they are usually black with white spots and spines. These spines persist into the pupal phase.
At higher temperatures around 32 degrees Celsius (90 degrees Fahrenheit), the pupal period of the red admiral is 6 days. At 11 to 18 degrees Celsius (51 to 64 degrees Fahrenheit) this period increases to 18 to 50 days. At even lower temperatures around 7 degrees Celsius (45 degrees Fahrenheit), the pupal period lasts between 47 and 82 days. The pupae are bright scarlet at high temperatures and black with a smaller scarlet area at low temperatures. This differential coloration at various temperatures may explain why the summer form of the red admiral is brighter and more heavily pigmented than the winter form.
The primary host plant for the red admiral is the stinging nettle (Urtica dioica), but it can also be found on the false nettle (Boehmeria cylindrica). Certain plants of the families Compositae and Cannabaceae may also be used as hosts.
The red admiral is identified by its striking black, orange, and white wing pattern. On the dorsal side, its dark wings possess orange bands on the middle of the forewings and the outer edge of the hindwings. The distal ends of the forewings contain white spots. The ventral side of the wings are brown with patches of red, white, and black. The hind wings have a brown marbled pattern. The red admiral has summer and winter morphs. Summer red admirals are larger and more pigmented than winter morphs. The wingspan ranges from 1.75 to 2.50 in.
Male red admirals court females for several hours before they begin mating. Because of female choice, only males with territory have the opportunity to mate. Females select males with traits that will increase the mating success of their offspring. In order to maintain their territory, males must fly around and patrol the area dozens of times per hour. Only males of exceptional flying ability are able to prevent intruding males and successfully court females. 
Mating usually occurs in late fall or early winter following collective migration to southern regions with a warmer climate. The red admiral’s main host plant, stinging nettle, is most abundant during this migration. Larval development proceeds through winter and adults are first sighted in early spring. The new generation of adults migrates north before mating, because food is usually diminished by late spring. During migration, the red admiral flies at high elevations where high speed winds carry the butterfly, requiring less energy utilization.
Red admirals have color vision and can differentiate colors in the 440-590 nm range of the visible spectrum. They have compound eyes with a transparent, crystalline structure called a rhabdom which functions similarly to a human retina. These butterflies do not have filtering pigments in their rhabdom, so they cannot differentiate between colors in the 590-640 nm range. 
Spring temperatures in central England between 1976 and 1998 increased by 1.5 degrees Celsius and summer temperatures increased by 1 degree Celsius. Following this 22 year period of warming, the red admiral appeared 6 weeks earlier in the year. Of 35 species of butterflies studied in central England, the increase in the duration of flight period was most significant in the red admiral, exhibiting a 39.8 day increase in duration of flight period. These changes in migration time and length could result in an increased abundance of red admirals and a northward range expansion. Warmer climates could lead to an increase in time spent finding mates, laying eggs, and collecting nectar. Conversely, more frequent droughts associated with climate change would decrease egg survival and lead to habitat and host plant destruction.
In popular cultureEdit
- "Vanessa Fabricius, 1807" at Markku Savela's Lepidoptera and Some Other Life Forms
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- Merrifield, Frederic (1893-03-01). "II. The effects of temperature in the pupal stage on the colouring of Pieris napi, Vanessa atalanta, Chrysophanus phlœas, and Ephyra punctaria.". Transactions of the Royal Entomological Society of London. 41 (1): 55–67. ISSN 1365-2311. doi:10.1111/j.1365-2311.1893.tb02052.x.
- "HOSTS - The Hostplants and Caterpillars Database at the Natural History Museum".
- C., Daniels, Jaret (2003). Butterflies of Florida field guide. Cambridge, MN: Adventure Publications. ISBN 1591930057. OCLC 53046492.
- Bergman, Martin; Gotthard, Karl; Berger, David; Olofsson, Martin; Kemp, Darrell J.; Wiklund, Christer (2007-07-07). "Mating success of resident versus non-resident males in a territorial butterfly". Proceedings of the Royal Society of London B: Biological Sciences. 274 (1618): 1659–1665. ISSN 0962-8452. PMID 17472909. doi:10.1098/rspb.2007.0311.
- Stefanescu, Constantí (2001-10-01). "The nature of migration in the red admiral butterfly Vanessa atalanta: evidence from the population ecology in its southern range". Ecological Entomology. 26 (5): 525–536. ISSN 1365-2311. doi:10.1046/j.1365-2311.2001.00347.x.
- Mikkola, Kauri (2013-01-01). "The Red Admiral butterfly (Vanessa atalanta, Lepidoptera: Nymphalidae) is a true seasonal migrant: an evolutionary puzzle resolved?". EJE. 100 (4): 625–626. ISSN 1210-5759. doi:10.14411/eje.2003.091.
- Frentiu, Francesca D.; Bernard, Gary D.; Cuevas, Cristina I.; Sison-Mangus, Marilou P.; Prudic, Kathleen L.; Briscoe, Adriana D. (2007-05-15). "Adaptive evolution of color vision as seen through the eyes of butterflies". Proceedings of the National Academy of Sciences. 104 (suppl 1): 8634–8640. ISSN 0027-8424. PMID 17494749. doi:10.1073/pnas.0701447104.
- Roy, D. B.; Sparks, T. H. (2000-04-01). "Phenology of British butterflies and climate change". Global Change Biology. 6 (4): 407–416. ISSN 1365-2486. doi:10.1046/j.1365-2486.2000.00322.x.
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- Red admiral on the University of Florida / Institute of Food and Agricultural Sciences Featured Creatures website
- Red Admiral Butterfly: Large format reference quality (free) photographs Cirrus Digital Imaging
- HD video of Vanessa butterflies
- Red Admiral, Canadian Biodiversity Information Facility
- Red Admirals in California
- Butterflies and Moths of North America - Vanessa atalanta
- Butterflies of America - Vanessa atalanta
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