A22.03 Marine Borers 



1. Teredlnldae . Wo eyidence of Teredlnldae was recorded in the 

 panels of either the control or test series until late in 19^7. The 

 test panel remoTed November 15 > 19^7^ after having "been submerged for 



k moi^ths, showed 8 specimens of Teredo somersi up to i|-0 mm long. No 

 "borers were recorded in either of the next 2 months of the test, which 

 covered up to January 10, 19^8. On the "basis of these data, the attack 

 is rated as slight in 19^7^ and there was none at all in I9I+6. While 

 Teredlnidae occurred only in small numbers in a single test panel during 

 the "brief period covered "by this test, records of the William F. Clapp 

 Laboratories show that they are very destructive at other points in 

 Benauda. 



2. Limnoria . Limnoria were very active throughout the period 

 covered by the test and occurred in considerable numbers in all panels 

 of both the control and test series. Of the 19 control panels, 9 showed 

 a thousand or more tunnels, and one panel exposed from August 22 to 

 September 22, 19il-6 showed 3,500 tunnels. 



In November of 19^6, because of the destructiveness of Limnoria 

 at this location, it was requested that the panels on the test board 

 be removed and a new series installed on a U-month basis instead of on 

 the 8-month basis previously followed. This change was made on December 

 15* 19^6. After the fourth of this new series of panels was removed, 

 the test was interrupted again, for some reason that is not clear, by 

 starting another i)-panel series on July 10, 19^7. 



In the test panels, the Limnoria attack at the beginning of the 

 test increased rapidly in severity with each month's submergence. In 

 the first set of 8 panels submerged on February 19, 19ll-6, where a 

 panel was removed at the end of each month, the tunnels numbered 497, 

 2,500, i)-,600, ll-,000, 5,500, 7,800 and 15,200 respectively, the last 

 panel, which had been submerged for 8 months, being entirely destroyed 

 except for a piece approximately 1-|- in. square around one of the bolt 

 hol#s. The next 2 panels, which were submerged from March 22 to November 

 19 and from April 22 to November 19, respectively, also were almost 

 completely destroyed. The 2 succeeding panels, which were submerged for 

 only 7 and 6 months, respectively, also were attacked with extreme 

 severity. With the reduction of the period of submergence to k months, 

 however, the attack was less severe. The Limnoria attack at this location 

 rated as extremely severe in both 19^1-6 and 19^7. 



105 



