Rambles about Rio de Janeiro 73 



away. Here, too, I had the great pleasure of observing 

 the curious habits of the butterflies belonging to the 

 genus Ageronia, which invariably light head downward 

 upon the trunks of the trees, with their wings expanded ; 

 and here I heard them as they circled about emitting 

 that curious sound concerning which Bates, in his 

 A Naturalist on the Amazon, has written. Just how 

 these frail little creatures produce a loud clicking 

 noise as they dash about in the air is an unsolved 

 mystery. Here also for the first time I encountered 

 in life the curious butterflies belonging to the genus 

 Ithomia and allied forms. They seemed to be the 

 ghosts of living things, so thoroughly transparent are 

 their wings, and it was only by sharply noting the few 

 bright spots upon them that I was able to follow them 

 in their flight. Their pursuit seemed to be the chase 

 of the invisible. Besides the butterflies, which were 

 numerous when the sun was bright, there were many 

 species of gaily colored moths, which are diurnal in 

 their flight, and which hovered over flowers or flitted 

 up from among the herbage. Some of these moths 

 have a wonderful resemblance both in the form of their 

 bodies and their wings to the bees and wasps, among 

 which they feed upon the same food-plants. One of 

 the marvels of the insect world is the great moth 

 which is occasionally found about Rio de Janeiro, and 

 which is characterized by its remarkably prolonged 

 hind-wings, as well as by the beauty of its colors. It 

 is known by the scientific name of Eudcemonia semi- 

 ramis. 



Of the Hymenoptera there were many species. A 

 great black wasp (Pepsis) three inches in length was 

 quite common and very conspicuous when feeding on 

 the spikes of the blooming xanthoxylon. I captured a 



