Vol. XXV] ENTOMOLOGICAL NEWS 339 



of the Rio Reventazon at Juan Vifias descend steeply from 

 I200 to 760 metres (4000 to 2500 feet) at the river, and down 

 the canyon side tumble many small streams and rivulets, of- 

 ten in cascades and in falls of different heights. Where there 

 is slant enough the wet rocks nearby are draped with mosses, 

 maiden hair ferns, begonias, dwarf Selaginellas, Tradescan- 

 tias, a Streptocar pus-like plant, etc., or in quieter more shel- 

 tered places are Melastomes (Miconia), Commelina, etc. 

 Only at three such falls did we ever observe Thaumatoneura, 

 two of them at altitudes of about 3300 feet, the third at about 

 2500 feet. They were most abundant on the whole at one of 

 the former two falls, one whose perpendicular height was the 

 greatest of the three, perhaps 200-300 feet. We were puzzled 

 why these insects should not be found also at other streams 

 under generally similar conditions. An explanation of their 

 absence from one of these streams, the little Rio Naranjo, is 

 suggested in our diary: "At the Naranjo I saw a number of 

 lizards from two inches to a foot in length and these possibly 

 keep down the number of insects. At our two waterfalls 

 \i. e. where we frequently found Thaumatoneura] we have 

 seen no lizards." 



We observed the images of Thaumatoneura in June (23-28), 

 July 21 to August 3, September 28 and 29, when there was 

 an evident decrease in their numbers ; October r and Decem- 

 ber 2, 1909. In February (14-18), and March (21), 1910, 

 none could be found, but they were again visible in April. In 

 June, 1909, the males of pellucida appeared to be less numer- 

 ous than those of inopinata. All the males of Thaumatoneura 

 observed in July were pruinose, but two teneral females were 

 taken on August i. 



"Males, at least, often remain on the same spot for a long 

 time without moving — I should say for half an hour or longer. 

 Females seem less persistent, but one I timed was ten minutes 

 on the same bit of twig. Except in pairing males, the wings 

 of both sexes, when at rest, are held in the vertical position, 

 folded together but every now and then an individual will open 

 and then close its wings once or several times in succession." 

 "Standing at the bottom of the waterfall and looking up 



