It crouches stationary on a leaf or other level surface and exhibits an elaborate combination of form and colour, the posture it adopts and the character of its web so as to simulate accurately a patch of bird's excreta.

[4] Here is how the Scottish naturalist Henry Ogg Forbes described how he first came to discover the spider: The first specimen I got was in West Java, while hunting one day for Lepidoptera.

I observed a specimen of one of the Hesperidae sitting, as is often a custom of theirs, on the excreta of a bird on a leaf; I crept near it, intending to examine what they find in what one is inclined to consider incongruous food for a butterfly.

He was a believer in Charles Darwin's theory of evolution through natural selection but found it difficult to understand how the mimicry of a variable object like a bird dropping could have evolved.

The fact that it then in some way resembled a bird dropping was fortuitous and natural selection merely acted to enhance the similarity.