Vol. xxvi] ENTOMOLOGICAL NEWS. 295 



Studies on Costa Rican Odonata. 



VI. The Waterfall-Dwellers: The Transformation, External Feat- 

 ures and Attached Diatoms of Thaumatoneura Larva. 



By PHILIP P. CALVERT, PH.D., University of Pennsylvania, 



Philadelphia, Pa. 



(Plate XI) 



In number V* of these Studies we have described the adults 

 of Thaumatoneura and some of their habits. While we ob- 

 served motions on the part of females which, by analogy, we 

 interpreted as those of oviposition, we were never able to 

 detect the eggs or to obtain the young larvae from pieces of 

 roots and of moss in which we supposed eggs to have been 

 placed. We were more successful with older larvae. On 

 June 26, 1909, a few were found in among the roots that hung 

 in front of the rock of the farther, or lower, waterfall at Juan 

 Vinas, where they were constantly bathed in the water. On 

 June 27, 1909, while hunting over the rocks at the foot of the 

 higher, or nearer, waterfall, we found a large larva of the 

 same kind (No. 4 of the list on page 300) "crawling up out of 

 the water on to a big rock. This being a hopeful indication of 

 near transformation we secured him and carried him back to 

 the cabin where we rigged up an ingenious and home-like 

 stream for him in the fixing dish aided by a big stone and a 

 bottle." All these went to our headquarters at Cartago but all 

 died before they yielded the wished-for imago. We write of 

 them now as Thaumatoneura larvae by reason of proof ac- 

 quired ten months after their discovery. Then we had only 

 the presumption based on their occurrence at the same locali- 

 ties with the winged individuals. On August 2, at the nearer 

 waterfall, we found an exuvia which we took to be that of 

 Thaumatoneura. Search for larvae at the farther waterfall on 

 December 2 was unsuccessful. On March 23 and 26, 1910, 

 larvae were not rare on the rock face of the nearer waterfall 

 where it was kept wet by the spray and, on the 26th at least, 

 where there was a thin layer of organic mud on the rock sur- 

 face. A visit to the same fall on April 24 yielded twenty-two 



*Ent. News, xxv, pp. 337-348. Oct., 1914. 



