156 Journal of Agricultural Research voi. xvi, No. e 



CHARACTER AND EXTENT OF THE INJURY 



It was found that the mangrove borer attacks only living red mangrove 

 and casuarina. The casuarina trees attacked range from 2 to 6 inches in 

 diameter; those over 5 years old usually are not attacked, except high 

 in the tops or branches. Small casuarina trees are attacked near the 

 base as a rule. In case of small trees the trunk may be girdled before the 

 larvae attain their growth, and in most cases the damage is done before 

 the presence of the insect is noticed. Many casuarina trees were killed 

 at Miami Beach in 1915 (PI. 18, B) and more in 1916. The infestation 

 in 191 7 at Miami Beach was apparently less than in 191 6, it having been 

 estimated that among trees planted during the winter of 1916-17, within 

 half a mile of the mangrove swamp, not more than i tree out of 20 was 

 lost. 



In the mangrove swamp along Biscayne Bay many red mangrove 

 trees were found in 191 6 to have been killed by the borer. In 191 7 a 

 great accumulation of dead and stag- headed mangrove trees which had 

 been gradually killed by the borer was noted, and many newly infested 

 trees. In 191 8 many additional mangrove trees were found infested 

 and it was noted that the infestation extended for many miles north of 

 Miami. The dead trees and the stag-headed, partially killed trees, many 

 of which are of large size, are strikingly evident against the sky line. 



At Hobe Sound, Jupiter Island, Fla., which is farther north than 

 Miami Beach, quite a few casuarina trees were killed in 191 5; the trees 

 are nearly 5 years old and, hence, not so liable to attack. At this locality 

 the red mangrove is low and scrubby, being apparently too far north for 

 favorable growth. In the swamps near by the borer was found in the 

 red mangrove, but the infestation was not heavy. 



On the ocean keys or reefs south of Miami the red mangrove apparently 

 is not infested by C. tranquebarica. At Adam Key, about 27 miles south 

 of Miami, neither the red mangroves nor the casuarinas which have been 

 planted there are infested, and no damage to mangrove by the borer has 

 been noticed. On Key Biscayne, just south of Miami, there was for- 

 merly a heavy infestation in the casuarinas, but the trees have now 

 reached an age at which they are out of danger of further attack. In- 

 fested red mangroves apparently do not occur in swamps continuously 

 from Miami Beach to Hobe Sound ; therefore there are broken centers of 

 infestation. No infested trees have been found south of Key Biscayne. 



STAGES, HABITS, AND SEASONAL HISTORY OF THE BEETLE 



Although C. tranquebarica was collected by Mr. H. K. Morrison at Key 

 West in 1886 and by Mr. E. A. Schwarz on cordwood of red mangrove 

 at the same locality in 1887 and although the beetle has been known 

 to science since 1787, it appears that nothing has been recorded regard- 

 ing its various stages, seasonal history, habits, etc. 



