A53.05 Marine Borers 



1. Teredlnldae . Teredinldae ( Bankla setacea ) were more or less 

 active at all five locations, tut it is noteworthy that at each site they 

 failed to develop in the first k panels which were submerged on July I5 and 

 removed, one each month, up to November 15, 19*l-i|-. Moreover, on the control 

 panels they failed to develop for a much longer* period. No specimens 

 developed on the control panels until after February 20, 191^5, at the 

 Temporary Pier and Army Pier; after January -I6, 19k6, at the Permanent 

 Pier and Woody Island Pier; or after August 25, 19k6, at the Marine Rail- 

 way. It is quite evident, then, that Teredinidae simply did not occur 

 at these locations from the date of the beginning of the test to the 

 dates given above. 



The control panels at all five locations showed very scanty 

 development of Teredinidae over very brief periods in comparison to the 

 rather extensive attacks recorded in tiie test panels. It is, therefore, 

 difficult to determine the breeding season at these localities, although 

 it appears to extend from late February to the middle of September, late 

 October, or even to late December at locations where Bankia setacea is 

 active and very destructive, as is the case at the Teixporary Pier. 



At eJ.1 five locations, it was evident in each year of the tests 

 that Bankia setacea occurred in greatest munbers and was most destructive 

 in the lower panels of the test boards; namely, Nos. 8, 9, 10, and 11, 

 which would locate the TnaxImnTn attack close to the mud line. The detailed 

 figures on the occurrence of Teredinidae is summarized by locations as 

 follows : 



a. Temporary Pier . Teredinidae occurred as minute pits or 

 embryonic specimens in 7 of the 50 control panels and in 26 of the same 

 number of test panels, attaining a maximum length of k3^ mm in one of the 

 control panels removed on June 20, 19i^5, after having been submerged for 

 11 months. Panels 9 to 11, inclusive, were riddled in 19i^5; in 19U6, 

 panels 8 to 11, inclusive, were riddled. The attack at this location rated 

 very heavy both years. 



b. Permanent Pier . Teredinidae occurred as minute pits in 



5 of the 39 control panels in 191*6 and 19i<-7, but no specimens were recorded 

 in 19Mi- and 19lf-5. Teredinidae occurred in 35 of the 37 test panels, attain- 

 ing a maximum length of 35O mm in a panel removed on August I5, 1914-7, after 

 having been submerged for I3 months. None of the test panels was either 

 filled or riddled, although submerged for 11 months during 19l|-5 and 19^*6, 

 and for 12 months during 19l*7. The attack at this location rated moderate 

 in 1945, medium heavy in 191*6, but only slight in 1947. 



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