Glancy also describes his collector as a possible drill eradicator. He 

 suggests that a slightly soluble chemical which upon hydrolysis will release a 

 toxic gas be placed m the pocket of air in the inner recesses of the baffled cylinder. 

 He further suggests that a grease containing DDT copper, mercury, and arsenic 

 salts, or combinations of these, could be spread over the interior of the cylinder, 

 Drills crawling over these would absorb lethal doses of the chemicals, or, irritated 

 by them would withdraw within their shells carrying lethal doses closed behind the 

 operculum, and destruction would then be completed after the drills fell to the 

 bottom. The baffles within the cylinder are said to effectively diminish the dissipa- 

 tion of these substances into the ambient water outside. 



To what degree drills will be killed by moving into the cylinder even in the 

 presence of high concentrations of poisonous salts and gases has not been investig- 

 ated; nor is it reported. whether dead drills have been found on the bottom under 

 the cylinders Uro salpinx possesses keen chemoreceptors as judged by their 

 response to young oysters and it is likely that; at the first contact with the peri- 

 pheral areas of low densities of noxious substances they will retreat, and this 

 initial dose may not prove inactivating or lethal The response of drills to concen- 

 tration gradients of these substances and their lethal effects should certainly be 

 studied before the collector is used specifically as a drill eradicator. Great 

 caution should be taken that whatever poisons are used in the cylinders do not pass 

 into the sea water in quantities sufficient to harm other marine life or be incorpor- 

 ated jn the tissues of oysters making them unfit for human consumption. This may 

 occur, as has been pointed out, in the use of mercuric chloride, and possibly other 

 poisonous metal salts . Toxic gases which soon dissipate in the water would probably 

 be less harmful and more readily eliminated in the tidal circulation. 



It is probable that Glancy' s seed collector will be most effective, not in 

 destroying drills on the bottom, but in producing oyster seed free of drills through 

 the first growing season. This in itself will be a major accomplishment and a long 

 awaited contribution to oyster farming. In any event, studies on the possible use 

 of the collector as an eradicator should be pursued 



Biotu 



Cole (1951) writes that a possible biotic method of control of the oyster 

 drill which his group is investigating is the multiplication of final hosts of certain 

 trematode parasites which caus;. ttion of the drill. 



Chapman and Banner (1949) report that the drill may have a natural enemy 

 in an unidentified amphipod which ordinarily lives with no apparent harm to the 

 oysters in small tubes constructed on the outside of Olympia oyster shells. The 



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