tide was 2.5 ft, and the strength of the current as determined "by tidal 



flow was approximately one knot. The temp era tvire of the water 



at the time of installation was 70° F. There was said to he no pollution. 



A5G.O5 Marine Borers 



1. Teredinldae . Teredinidae , including Teredo sp . , were 

 extremely active and destructive at both locations, rating very heavy 

 at the second location and heavier yet at the first. They occurred in 

 all the control panels received from hoth locations, except the first 

 panel of Test Board No. 2, which clearly indicated that they were "breeding 

 throxAghout the year. While many of the control panels from hoth test 

 hpards showed only pits or minute specimens, tunnels up to 70 mm in 

 length were recorded in a panel of the hoard at the second location. 



One control panel which had heen ecrposed from Octoher 10 to November 

 10, 19^6, at the first location was riddled, and one at the second 

 location that had "been exposed from January 10 to February 11, 19^7 » 

 was filled. 



All five test pajiels that were removed during the months of May 

 to November (December panel was lost), after h, 5, 6, 7, and 8 months' 

 exposure, respectively, at the first location were either filled or 

 riddled, with some specimens up to 190 mm in length. At the second 

 location, all the test panels that were removed from August to December 

 after 7 or 8 months' exposure, were more or less filled, with speci- 

 mens running up to 220 mm in length. It thus appears that the period 

 of most active growth ranges from May to December. 



2. Limnoria . Llmnoria also were active at both locations through- 

 out the period for which the test boards were operated, occurring in 



all panels received, both control and test, except in the first panel 

 of the control series at the second location. At the first location, 

 the attack in the control panel submerged from October 10 to November 

 12, 19^6, was exceptionally severe and rated medium heavy. At the 

 second location, the attack was exceptionally severe in 2 of the 

 control panels, rating heavy in one panel submerged from January 10 to 

 February 11, 19^7^ and medium heavy in one inadvertently exposed for 

 two months from April 10 to June 10, 19i^7• Such outstanding attacks 

 in control panels demonstrate the ability of Limnoria to destroy wood 

 very rapidly in comparatively short periods. 



In the test panels, the Limnoria population fluctuated within 

 certain limits but, in general, maintained a fairly higja level, with 

 the maximum attack at both locations ranging from the lower limit of 

 the hea-vy rating in 19k6 to well up in the same rating in 19^7' 



238 



