DRAGONFLIES OF JAMAICA* 



By Charles B. Wilson 



The dragonflies of Jamaica are subject to peculiar en- 

 vironmental conditions which exert an important influ- 

 ence on their distribution and abundance. Nearly all of 

 the Odonata demand quiet fresh water for the laying of 

 their eggs and the rearing of their young. But such 

 bodies of water are comparatively rare on the island, are 

 widely scattered with long intervals between, and are 

 usually small and densely filled with aquatic life, both 

 animal and vegetable. 



All the rivers of Jamaica and most of the streams have 

 far too swift a current for dragonfly larvae except close 

 to the ocean, and only one or two species frequent them. 

 The first result is that practically the entire dragonfly 

 fauna is confined to the immediate vicinity of the isolated 

 ponds and quiet streams. 



Hence there is much crowding and as a second result 

 some of the dragons like Trithemis umhrata and Orthemis 

 ferruginea utilize almost any pool of water they can find, 

 in company with the mosquitoes and gnats. And they 

 may often be seen depositing their eggs in the tiny rain 

 pools which collect in the hollows of the honeycombed 

 limestone rocks. 



Again some of the damsel flies like Micronympha ram- 

 hurii and Anomalagrion hastatum frequent for the same 

 purpose the water pools formed inside the wild pines 

 (Bromelia) . 



There is always plenty of water here and enough mos- 

 quito and gnat larvae to furnish the damsel nymph with 

 an abundance of food. But the water in the rock pools 

 frequently dries up, and it is doubtful whether any of the 

 dragon larvae, hatched in those pools, are ever transformed 

 into adults. 



* Notes from the Johns Hopkins University Laboratory at Mon- 

 tego Bay, Jamaica. B. W. I., summer of 1910. 



