Monsoon rain was lashing heavily that day. That morning when there was a brief respite from the rain, I went home to grab a quick cup of coffee, I saw these Common Mormon (Papilio polytes) mating on the citrus plant. Leaving the coffee aside I grabbed my camera and rushed to get these photos. The place where these butterflies were mating was a tricky one. It was on a precarious ledge so I had very little space to maneuver myself. They were hanging from a bush which had only one clear opening, rest of the surrounding was covered by leaves. Light was pretty abysmal. As I had sold my 5D Mark II that time I had only one camera. I fitted my Canon EOS 1D Mark IV with Canon EF 100 f/2.8L IS USM. For the light I used ExpoImaging Ray Flash Adapter on Canon Speedlite 580EX II flash.
The female Common Mormon was hanging from the citrus leaf and male was attached to the female. Weight of the both these butterflies was carried by female. Even though I was not expecting them to fly off in that position I did not want to disturb their coitus. Using the only window of opening I had, I tried to take photograph before the rain resumed.
At the first sight both butterflies look so dissimilar. That is because the female Common Mormon is mimicking the Crimson Rose (Atrophaneura hector) butterfly. Common Mormons are not toxic but by mimicking the toxic butterfly they escape being eaten by birds which mistake them for Crimson Rose.
Henry Walter Bates, determined that these multi-morph females are mimicking other butterflies. In the areas where the Mormons occur, there are other species of butterflies that look like one or another morph of the Mormon females. These other species feed on toxic plants such as Aristolocia, which renders them unpalatable to predators. The Mormon females, which are palatable, mimic the unpalatable model thus gaining protection from predators that mistake them for the other bad tasting species. This type of mimicry has become known as Batesian mimicry in honor of Bates who first described it in 1862.
The male has one morph only. It is a dark-coloured swallow-tailed butterfly. The upper forewing has a series of white spots decreasing in size towards the apex. The upper hindwing has a complete discal band of elongated white spots. It may or may not have marginal red crescents. The males are smaller in size than the females.
The female of the Common Mormon is polymorphic. In South Asia, it has three forms or morphs. These are as follows:
- Form romulus: This female form mimics the Crimson Rose and is common over its range. It is not such a close mimic as the previous form being duller than its model, the Crimson Rose. It is easy to differentiate the mimics from models by the color of their body—the models are red-bodied and the mimics are black-bodied. This is the form you are seeing in these photographs.
- Form cyrus: This form is similar to the male, differing in that it always has strongly marked red crescents. It is the least common of the three forms. It is normally abundant where the Common Rose or Crimson Rose do not occur, such as in Himachal Pradesh around Shimla.
- Form stichius: This female form of the Common Mormon mimics the Common Rose very closely. This is the commonest form wherever the Common Rose flies.
Common Mormon butterfly is considered as the classic example of Batesian Mimicry in which edible species resemble unpalatable butterflies in order to escape being eaten by predators. The populations of the mimicking morphs of the Common Mormon are much smaller than that of their models – the Common or Crimson Rose. This is in order to allow first time predators a much greater chance of preying upon the unpalatable model in the first instance and thus learning of their in-edibility.
Larger populations of mimics could result in the edible Common Mormon mimics being sampled the first time by predators. If this should happen, the predator may not realize that butterflies of that color and pattern are protected by the poisons they ingest; thus dramatically reducing the effectiveness of this scheme of protection.
If you are wondering how these butterflies got their name, here is an interesting fact. Harish Gaonkar, of the Natural History Museum in London, recently wrote
the origins of giving common English names to organisms, particularly butterflies for tropical species started in India around the mid 19th century.The naming of Mormons evolved slowly. I think the first to get such a name was the Common Mormon (Papilio polytes), because it had three different females, a fact that could only have been observed in the field, and this they did in India. The name obviously reflected the Mormon sect in America, which as we know, practiced polygamy.