258 IN THE GUIANA FOREST. 



they are grown well drained. Few have made any 

 provision against the blood-sucking loranths or 

 scale-insects, and consequently suffer much, hardly 

 ever succeeding in throwing them off without 

 assistance. Those which have been in cultivation 

 for long periods are especially weak, while others 

 coming from a different environment have never 

 had the same pests to contend with, and are there- 

 fore unfitted to their new surroundings. The 

 loranths seem to know this, and flourish in the 

 utmost luxuriance among their branches, killing 

 them very quickly if man does not interfere. The 

 number of mango trees, for example, in the city 

 of Georgetown and its vicinity which are always 

 suffering from the attacks of a pretty stellate scale 

 and a fungus like the well-known London " blacks " 

 is enormous. Which comes first in the field is 

 doubtful, but, speaking generally, we think the 

 disease commences with a general weakness of the 

 whole tree. Then probably comes the scale insect, 

 fastening itself on the under side of the leaf, and 

 increasing the debility until a state of general 

 ill-health is produced. Finally the fungus covers 

 the upper surface with its black film, which here 

 and there peels off and hangs down in a most 

 ragged and unsightly manner. The tree struggles 

 to get rid of its tormentors, and perhaps, if it could 



