should prove useful as an expedient. Haskm (pers. com.) cites an application of 

 this method of control in Delaware Bay Durn g the past four years such light 

 natural sets of oysters have occurred in the upper less saline zone where Urosalpinx 

 exist in Delaware Bay that Urosalpmx have destroyed them almost entirely. In 

 October, 1953, 5, 000 bushels of heavily spatted 1953 Cape Shore set (averaging about 

 2, 000 spat per bushel) was transplanted to this area, and to date (November, 1954) 

 the destruction of the spat by drills has been negligible . 



Sharply pointed objects 



In Japan Suehiro (1947) recommends the use of the chestnut burr on the rope 

 of the collector string to prevent the climbing of the Japanese drill Rapana. He 

 found that the soft footed drills would not cross the sharply pointed barriers. 



Exposure on intertidal bottom 



From preliminary studies in Seaside, Virginia, where he found that 

 oyster setting occurs as high as three feet above low water mark but that destruc- 

 tion by drills is curtailed rather abruptly one to two feet above low water, Mackin 

 (1946) suggests that in this region the drill may be controlled by utilizing the drill 

 free zone for the culture of oysters . He admits that such high grounds are scarce, 

 and that since the erection of artificial elevated surfaces is costly, available areas 

 must be exploited to the fullest to compete economically with good natural subtidal 

 grounds . 



BENEFICIAL ASPECTS OF THE DRILL 



Latham (1951) emphasizes in an exhaustive treatment of the ecology and 

 economics of vertebrate predator management that the most destructive predators 

 may be beneficial under certain circumstances. This seems to apply to U. cinerea . 

 As Glancy (1953) points out, and with reason, the destruction of heavy sets of spat 

 on marketable oysters is desirable since such sets render these oysters practically 

 unmarketable , When dense sets do survive on adult oysters it is usually more 

 profitable to handle the population as seed. He reports that in some of the southern 

 states one of the drawbacks to oyster culture is the continual setting and survival 

 of young oysters on older oysters, resulting in a product winch, if used at all, can 

 be handled only in canneries . 



GENERAL DISCUSSION 



One is led to believe from early reports (Ingersoll, 1881; Bur, Stat. N.J., 

 1902) that the oyster occurred in unusual abundance along the eastern coast of the 

 United States during the 17th century. But mention of Urosalpinx is not found until 



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