Haskjn (1950) in work perfoimed in 1935-1937 which demonstrated that chemical 

 attraction plays a dominant role in food selection by drills, was able to suggest 

 that his findings might provide clues in the discovery of effective baits for traps 

 in the control of Urosalpmx 



Loosanoff, Nomejko and Miller (1953) initiated the first and only known wide 

 scale search for compounds which might be utilized in the control of U. cinerea. 

 They began experiments in 1947 seeking substances which would prove inexpensive,, 

 affect oyster enemies injuriously and remain harmless to man and to commercial 

 marine organisms . To date over 1, 000 compounds have been screened under 

 meticulously controlled laboratory conditions. The screening procedure involves 

 the incorporation of the test chemical in agar blocks which are then placed in trays 

 of sea water with drills . The behavior of the drills is observed continuously during 

 the experiment. Of the total number of compounds tested about 50 show promise as 

 repellents and approximately 60 as attractors of Uro salpinx After further testing 

 the latter may be useful as bait in drill traps. These investigators also discovered 

 several toxic compounds which in comparatively light concentrations cause the 

 death of drills A number of chemicals were discovered which may be useful in an 

 indirect means of control . These upon addition in small quantities to sea water 

 around drills caus e the soft parts of the drills and of other gastropods to swell 

 far out of the protecting shell. During this stage, which usually lasts several hours 

 to several days, the snails are incapable of locomotion and of contraction and -thus 

 are ready prey to crabs which suffer no ill effects. Likewise oysters, clams, and 

 mussels are unaffected by these relaxing substances The valuable information 

 accumulated by these researchers, though extensive, is based entirely upon pre- 

 liminary laboratory experiments, thus no final recommendations are yet available. 

 Numerous additional screening tests and actual field experiments are mandatory 

 before large scale field applications are possible The search for new compounds 

 and the effect of these compounds on oyster drills is being continued (Loosanoff, 

 pers. com.) at the U. S. Fish and Wildlife Biological Laboratory, Milford, 

 Connecticut 



Physical and chemical barriers 



J. B, Glancy, West Sayville, New York (pers. com.) has invented a device 

 (for which he is making patent applications in a number of countries) which he 

 describes as an "oyster seed collector and drill eradicajtor" . The collector, by 

 interposing a physical and a chemical barrier between drill infested bottom- and 

 elevated oyster seed a prevents the crawling of drills onto oyster seed. 



Glancy's collector is constructed as follows: a wide spreading base of two 

 cross bars of angle iron supports a central vertical pipe about a foot in height which 

 in turn underpins a second set of shorter cross bars . About 12 chicken wire bags 



121 



