236 A YEAR OF COSTA RICAN NATURAL HISTORY 



togaster modestus. Both had lost, weeks before, the three 

 conspicuous gills at the hind end of the abdomen, while other 

 larvae of the same species apparently about the same age 

 and from the same bromellad at Juan Vifias still retained 

 the gills. Absence of these organs seemed to make no differ- 

 ence in the transformation of the former two individuals, 

 which accomplished this feat perfectly. 



This and other bromeliad-dwelling larvae had been kept 

 in captivity, under the conditions we have described, for 

 nearly four months. They had been fed with blood-worms, 

 but although we did actually see them swallow some of the 

 worms they never seemed to eat many. Compared with 

 other dragonfly larvae, they were very abstemious and we 

 could not see how they obtained enough nourishment to 

 carry them through four months and a successful transfor- 

 mation at the end. 



In the afternoon of April 26 we walked along the railroad 

 from Juan Vifias station to a fresh clearing planted with 

 beans. Here the ground sloped more gradually than in 

 many parts of the bank below the railroad, and on the edge 

 of the clearing was a tree with some large bromeliads that 

 seemed to be accessible. So thither we went with our rope 

 and big knife, pail and bottles, to secure the vast horde of 

 Mecistogaster larvae that ought to be living there. Arrived 

 at the bean patch we found a man busily weeding and asked 

 his permission to go through, which was readily granted. 

 We worked all afternoon on the various clumps of bro- 

 meliads and found a few larvae of Mecistogaster, with an 

 accompanim.ent of m.osquito larvae, spiders, cockroaches, 

 slugs, planarians, earthworms, and the big-jawed black ants. 



On April 28 we passed the remains of the bromeliad cluster 

 which yielded the larvae from which M. modestus transformed 

 in our room at Cartago on April 4 and 6. A single male 

 of this species was sitting on the tip of a leaf and was easily 



