Plain Tiger

Monarchs and Tigers belong to the genus Danaus. They are large butterflies, characterised by their orange wings, which have a black apex, and white subapical spots. On the males there is a patch of raised androconial ( pheromone emitting ) scales on the hindwings.
All butterflies in this subfamily are thought to be toxic or distasteful to avian predators. Their bodies contain toxins derived from the larval foodplants, often supplemented by further toxins derived from pyrrolizidine alkaloids in adult food sources.
The bright colours of the butterflies advertise their poisonous qualities to birds in the same way that the bands of yellow and black of wasps advertise the fact that they can sting. Any bird that suffers the unpleasant experience of tasting a Danaus is unlikely to attack any similarly coloured butterfly, so the advertising is beneficial to chrysippus - and to species which mimic it, such as Hypolimnas misippus.
This form of defence is called Batesian mimicry. It is only effective because the toxic species far outnumber the non-toxic species. If the situation was reversed, and most of the butterflies attacked were palatable, the mimicry would serve no purpose.