Common Mormon
Papilio polytes romulus, Cramer

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Male Common Mormon (form cyrus) on wet soil

Description
A large butterfly with a wingspan of 80 - 115 mm. The male is black and has small creamy white markings on the outer margins of both wings. On both sides of the hind wing, there is a central band of creamy white spots.

This is an interesting polymorphic species. The male has only one colour form but the female has three, two of which are mimics. The typical female form, cyrus, resembles the male. It is larger than the male and paler in color. The form stichius mimics the unpalatable Common Rose. The third form, romulus, mimics the unpalatable Crimson Rose. The 2 mimics are quite variable and frequently display aberrations including gynadromorphs (part male, part female).

Similar species
Crimson Rose - The following characteristics distinguish it from romulus: a) the abdomen is velvet black with bright red towards the distal end; b) on the hind wing, there are two rows of crimson coloured lunular spots that are evenly spaced between and within the rows; c) there is no tornal spot on the hind wing; d) the tails are narrower and are of uniform width; and e) the forewing width is relatively uniform along most of its length.

Common Rose - The following characteristics distinguish it from stichius: a) the abdomen is velvet black with bright red towards the distal end; b) on the hind wing, the submarginal lunular spots are red with considerable black scales; c) no tornal spot on hind wing and d) the markings at the center of the hind wing are off-white in colour.

Status, distribution and habitat
Form cyrus is the commonest of all, and is widely distributed and seen all year round. This species occurs in many habitats, but prefers those providing a mix of open spaces and wooded areas.

The female forms that mimic the unpalatable models are never abundant in any season, though the models that they mimic are plentiful. Since unpalatable models occur in much larger numbers in the population, predators are more likely to encounter and flavor the distasteful ones during their search for prey. Such encounters probably teach the predators very quickly which ones to avoid. As a result, they are just as likely to stay away from the similar looking mimics, conferring a survival advantage to the 'Cheats'.

The strategy of the cheats to disguise themselves goes even further. Their frequency of occurrence is finely tuned to the relative abundance of their models. For instance, the models do not occur at the highest elevations, and neither do their mimics. At these elevations only the non-mimetic form cyrus is encountered. On the other hand, in the mid-country hills around Kandy, the Crimson Rose is the commoner of the models and so is its mimic, form stichius. In the dry and intermediate zones, however, where the Common Rose and the Crimson Rose are equally common, both mimetic forms occur with about equal frequency.

Habits
The male and the female form cyrus fly fast in a zigzag manner within a few feet above ground. It is a rather restless butterfly and is rarely seen settled except when nectaring.  It is common to see them fly hurriedly from one bush to another, or perhaps along a hedge row before turning into the thickets.  The mimics on the other hand, fly slowly and leisurely in their search for nectar, mates or larval host plants. 

All the forms nectar on short herbs and shrubs and are rarely seen high up in the canopy. They spends the night settled on some vegetation, often quite close to the ground, with open wings.

Early stages
The larvae feed on members of the Rutaceae. Citrus and the curry leaf plant are the most widely used larval host plants.

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