NATURAL OYSTER BEDS OF DELAWARE. 29 



Although in the absence of other food the drill will attach and 

 sometimes kill oysters of marketable size, it invariably attacks smaller 

 ones by preference. Seed oysters 2 or 2£ inches in diameter are com- 

 paratively immune, and in places where the drills are particularly 

 troublesome such seed should be planted in preference to smaller. 

 Although such is not known to be the case in Delaware, there arc 

 localities in which it is useless to plant shells or other cultch, as the 

 spat is drilled before its shell has lost its first paperlike thinness. 



The drill is a difficult enemy to combat. Where it is sufficiently 

 abundant to be a menace on private beds the oysters are usually 

 dredged up and the drills removed by hand and destroyed, after 

 which the oysters are again laid down. Much can be done by destroy- 

 ing the drills and their egg capsules wherever found. The common 

 practice of some Delaware planters of depositing rough seed on their 

 beds undoubtedly helps to maintain the abundance of the drill. 



