Knowing our butterflies: The stunning yet common Blue Tiger
Marianne de Nazareth
This species of butterfly migrates extensively during the monsoons in southern India and toxic compound from can cause heart attacks when ingested in large dosage.
The Blue tiger is a delight to the eye. They have a wingspan of 75 to 105 mm. The head, antennae and thorax is brownish black in colour, with white dots on the head and neck. The Blue Tiger Butterflies have brownish black upperparts, with bluish white semi hyaline spots and streaks. They have two pairs of filaments.
Vinithashri Gautam who has taken one of the pictures says,” The Blue tiger is a nymphalid butterfly a Common butterfly occuring through- out the year. Fond of flowers , the butterfly feeds on plants belonging to Asclepiadaceae family. These butterflies can be photographed easily while they are feeding on flowers.”
The male and female according to a butterfly site are different. The male has a small brown flap on the hind wing and the female has continued blue colour instead of the flap. They have many irregular spots on their wings and the pattern of spots is important in distinguishing this species from other Tiger butterflies and their mimics.
Nitin R a butterfly enthusiast says, ” The Blue Tiger (Tirumala limniace), is a butterfly found in the Oriental Region of the World. We have one subspecies which occurs in India (Tirumala limniace exoticus). Blue tigers belong to the Nymphalidae family (brush footed) of butterflies. They are one among the species of the milkweed group (the others being plain and striped tiger and the crows). They feed on milkweed plants and they are known to sequester toxins from the milkweed plant and become toxic. ”
This toxicity according to Nitin is used as means of defence against vertebrate predators like birds and lizards. The toxic compound in them is known to cause heart attacks when ingested in sufficient quantities. They are also involved in the only longitudinal migration of insects known the world. Blue tigers, along with common crow, double branded crow and dark blue tigers migrate from the Western Ghats on the onset of South West Monsoon to the Eastern Ghats and return from the Eastern Ghats to the Western Ghats on the onset of North East Monsoon. If one is observant, this migration can be enjoyed as seeing so many hundreds of butterflies together is a spectacular sight.
It is interesting to watch the butterfly change from the lava stage to the adult butterfly. In the larvae stage the colour of its body is yellowish-white. Black spots are present on head, feet and claspers. The 3rd and 12th segments, each have a pair of fleshy filaments, black and greenish white. While the length of larva is around 1.20 cm.
Not many of us city dwellers notice this, but In the Pupa stage the colour of body is green with gold scattered spots and a beaded dorsal crescent. The males are smaller than the females and can at once be distinguished by the presence of a pendulous, flat pouch near the cell of hind wing. This pouch interestingly contains scent scales.
Nitin explains that there are many species of butterflies which mimic blue tigers. Blue tigers along with Dark blue tigers and glassy tigers form a Mullerian mimicry system. Common Wanderer (Pareronia hippia) and Dark Wanderer (Pareronia ceylonica) females mimic blue tigers and the female of Common Mime (Papilio clytia) which mimic the blue tigers.
So go out in your garden if you have one in South India and you might get lucky to see a Blue Tiger.
Featured image: Blue Tiger©Vinithashri Gautam