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able is the noise produced by various species of the Nymphalid genus 

 Ageronia, to which attention was first called by the late Charles Darwin 

 in his "Naturalists Voyage Bound the World." This was his famous ex- 

 pedition in H. M. S. Beagle, which enabled him to contribute so largely 

 to our knowledge of the fauna of the various countries visited. During 

 his stay in Brazil he paid considerable attention to entomology, and his 

 notes upon the singular habit of Ageronia are worth transcribing in 

 full. He says : 



I was much, surprised at the habits of Pajjilio feronia (Ageronia feronia of later 

 authors). The butterfly is not uncommon, and generally frequents the orange 

 groves. Although a high flier, yet it very frequently alights on the trunks of trees. 

 On these occasions its head is invariably placed downwards, and its wings are ex- 

 panded in a horizontal plane, instead of being folded vertically, as is commonly the 

 case. This is the only butterfly which I have, ever seen that uses its legs for running. 

 Not being aware of this fact, the insect, more than once, as I cautiously approached 

 with my forceps, shuffled on one side just as the instrument was on the point of clos- 

 ing, and thus escaped. But a far more singular fact is the power which this species 

 possesses of makiug a noise. Several times when a pair, probably male and female, 

 were chasing each other in an irregular course, they passed within a few yards of 

 me, and I distinctly heard a clicking noise, similar to that produced by a toothed 

 wheel passing under a spring catch. The noise was continued at short intervals, 

 and could be distinguished at about 20 yards distance. I am certain there is no error 

 in the observation. (Nat. Voyage, Appleton's edition, p. 33.) 



As a boy, I had read this interesting note by the great naturalist, 

 and in the last mouths of the year 1866 I had, during a stay of four 

 weeks in Panama, the opportunity of observing for myself this curious 

 butterfly habit. The species Ager. feronia, A. ferentina, and A. amphi- 

 nome, and more especially the two former, are particularly common in 

 the forests around the city of the Isthmus, and it is not possible to 

 walk a mile through them without meeting with many examples. The 

 sound made by the first-named species is like that of the next, and 

 somewhat recalls the noise produced by a boy's imitation of the old 

 watchman's rattle. It is a decided " click," " click," very often repeated, 

 and can be, as Mr. Darwin says, distinctly heard at the distance of 

 20 yards. Indeed, I should be disposed to extend this to at least 40 or 

 50 yards on a clear day, and when no wind could carry the sound away. 

 The noise of A. amphinome is a heavier and more grating sound, and 

 the two species can be readily distinguished without being seen. The 

 trees on which they are accustomed to sit are species of Cassia or 

 Mimosa, and their gray color, closely resembling that of the bark, 

 renders them rather difficult to be seen when at rest. 



I once went into the forest some time after sundown to see if they re- 

 mained at night upon the trunks of the trees, as moths do in the day- 

 time, but I could not find a single specimen, although many trees on 

 which I had noticed them during the day were carefully examined. In 

 a footnote to page 33 of Mr. Darwin's narrative, he quotes Mr. Edw. 

 Doubleday as having described before the Entomological Society, March 



