Papilio demoleus is a common and widespread swallowtail butterfly. The butterfly is also known as the lime butterfly, lemon butterfly, lime swallowtail, and chequered swallowtail. These common names refer to their host plants, which are usually citrus species such as the cultivated lime. Unlike most swallowtail butterflies, it does not have a prominent tail. When the adult stage is taken into consideration, the lime swallowtail is the shortest-lived butterfly, with male adults dying after four days and females after a week. The butterfly is native to Asia and Australia, and can be considered an invasive pest in other parts of the world. The butterfly has spread to Hispaniola island (Dominican Republic) in the Western Hemisphere, and to Mahé, Seychelles.
The butterfly is tailless and has a wingspan 80–100 mm.: 52 Above, the background colour is black. A broad, irregular yellow band is found on the wings above, which is broken in the case of the forewing. Besides this, the butterfly has a large number of irregular spots on the wing. The upper hindwing has a red tornal spot with blue edging around it.
As the caterpillar ages, its hunger for leaf tissue continues to grow.
Detailed description as given by Charles Thomas Bingham in 1905:
This butterfly is an avid mud-puddler and visitor of flowers. It basks with its wings held wide open on tufts of grass and herbs, and generally keeps within a metre of the ground, even on cloudy days. It relies on its quick flight for escape.It has a number of modes of flight. In the cool of the morning, the flight is slow considering that it is an edible and unprotected swallowtail. As the day progresses, it flies fast, straight, and low. In the hotter part of the day, it may be found settling on damp patches, where it will remain motionless, except for an occasional flutter of wings, if not disturbed. It is also a frequent visitor of flowers in gardens, where it shows a preference for flowers of smaller herbs rather than larger plants such as the ubiquitous Lantana with its plentiful blooms. It can be found swarming in the groves of its food plants.
Research on freshly emerged imagines of P. demoleus showed that they have an inborn or spontaneous preference while feeding for blue and purple colours, while the yellow, yellowish-green, green, and blue-green colours are completely neglected.
The number of generations of P. demoleus is dependent upon temperature – near the equator, nine generations have been recorded, while in warm temperate China, five generations have been recorded. In the ideal conditions of a laboratory, a generation has been recorded to take place in just over 30 days. The typical time for one generation of P. demoleus to mature in the field ranges from 26 to 59 days. In cold climates, the lime butterfly is known to pass the winter as pupae. Typically, the butterfly undergoes five instars as a caterpillar.
The female butterfly goes from plant to plant, laying a single egg at a time on top of a leaf, which it holds onto with its legs, and flies off as soon as the egg is laid. The egg is round, light yellowish in colour, flattened at the base, smooth-surfaced, and about 1.5 mm in height. Fertile eggs develop a small red mark at the apex.
The newly hatched caterpillar stays in the middle of the upperside of the leaf. The first instar of the caterpillar is black, with a black head and two rows of subdorsal fleshy spines. The second, third, and fourth instars are dark, with a glossy, dark-brown head, and white markings on the eighth and ninth segments of the caterpillar, which resemble a white patch of uric acid deposited in a bird's droppings, helping them escape predation while remaining in moderately open places.
As the instars progress, this resemblance is lost. From the fifth instar onwards, the caterpillars now turn cylindrical in shape, tapered towards the rear, and uniformly pale green in colour with a white subspiracular band. An additional black band is developed on the fourth and fifth segments with two black and two bluish spots on them. The eighth and ninth segments, which earlier provided the camouflage markings now develop a brown and white band. At this stage, the caterpillars are forced to inhabit secluded places.
The pupa, which is rugose (wrinkled), stout, and 30 mm in length, has two projections to the front on its head and also one on its thorax, and resembles that of the common Mormon (Papilio polytes), the difference being that the common Mormon pupa has a deeper cut between the projections and its abdomen is more protruded on the sides, having a small point.
The pupa is dimorphic with regards to colour, with the colour developing according to the prevalent colour and texture in the background. The green morph, which is found amongst green vegetation and smoother textures, is light green and unmarked or with yellow dorsal markings. When situated among brown or dry objects, the pupa tend to turn light grey brown to pink brown and develop cryptic dark brown and black striation.
The adults fly in every month, but are particularly abundant during and after the monsoons.
Captive breeding of P. demoleus in Riyadh has revealed these data about the lifespan of various stages at that locality:
The lime butterfly is an economic pest on many cultivated citrus species in India, Pakistan, Iraq, and the Middle East. Due to its history of successful dispersal and range extension, the lime butterfly is likely to spread from its original point of introduction in Hispaniola in the Caribbean to neighbouring Florida, Central America, and South America. Due to its capability for rapid population growth under favourable circumstances and its having been recorded to have five generations in a year in temperate regions of China, it is considered a serious potential threat. The caterpillars can completely defoliate young citrus trees (below 2 feet) and devastate citrus nurseries. In mature trees, caterpillars may prefer young leaves and leaf flush.
Hand-picking of caterpillars and spraying with endosulfan 35 EC (2 ml/10 litres of water) were the recommended means of pest control by Indian government agencies and agricultural colleges, however, endosulfan has since been banned by the Supreme Court of India.
