title: Byasa nevilli
text: # Byasa nevilli
  
  Byasa nevilli, the Nevill's windmill, is a butterfly found in India that belongs to the windmills genus (Byasa), comprising tailed black swallowtail butterflies with white spots and red submarginal crescents.
  
  ## Range
  
  North east India (Assam), Myanmar (Shan states) and western China.
  
  ## Status
  
  It is very common in western China and very rare in India. This butterfly is protected in India though it is not known to be threatened.
  
  ## Taxonomy
  
  No separate subspecies have been described.
  
  ## Description
  
  The wingspan is 100–120 mm. In appearance it is similar to the great windmill (Byasa dasarada), but is smaller. The tail is not red-tipped. It also resembles the great windmill subspecies B. d. ravana, Moore, but is smaller, with the markings also proportionately smaller. The male differs as follows: the subterminal series of lunules on the hindwing are crimson or vermilion red, never white or partly white as in B. d. ravana; sexual abdominal fold within white, not blackish brown; the subterminal red lunule in interspace 3 very often missing. Female resembles the male rather than the female of B. d. ravana but the white rectangular markings in interspaces 5 and 6 are whiter. From B. d. ravana female it differs in the complete absence of the white discal spots in interspaces 1, 2, 3 and 4. In both sexes the tail is black without any red spot.
  
  