658 U. S. BUREAU OF FISHERIES 
Mr. Tuompson. I would like to ask about the drills. Has anyone 
any idea as to how fast they grow? It seems to me that if the rate 
of growth is very slow, and they move very little, it might be possible 
to exterminate them. 
Doctor Frprertent. The rate of growth is one of the problems that 
will be taken up this spring when the drill begins to spawn. 
Mr. Pryruercu. Our observations at Milford Harbor indicate 
that the adult drills cover the shells with their capsules. They 
hatch at about the same time that the oyster does. It seems that 
these little yellow drills are just large enough to keep pace with 
the growing oyster. In Milford Harbor we found 60 of these tiny 
drills that had drilled something like 120 of the smaller oysters in 
one small area. 
Mr. Tuompson. If that is true, I should think you could study the 
problem of growth simply by a study of the length. 
Mr. Pryruercu. We very likely could, although we find all sizes 
in the sounds. 
Mr. Gutseix. I would like to ask another question with regard 
to the oyster. As I understand it, the stimulation of the female to 
spawn is produced through the addition of sperm. Does that occur 
in the case of those that are unripe as well as those that are ripe? 
Doctor Gatrsorr. Oh, yes. The difference is that if the female is 
not quite ripe the reaction may last for 10 or 12 hours. This reaction 
has been recorded by a slow-going kymograph. In one case the 
reaction recorded required six hours. 
Mr. Rancutrre. Is my understanding correct, Doctor Galtsoff, that 
the artificial stimulus to spawning might be used in Long Island 
Sound in certain seasons when there is no natural spawning? Might 
it be possible to produce spawning in years when otherwise no spawn- 
ing would occur ? 
Doctor Gatrsorr. Probably Long Island Sound is quite a good 
locality. I certainly believe that it could be done in Great South 
Bay and that the artificial impulse to spawn can be made of practical 
use. 
Mr. Tuomeson. I would suggest that one of the best places to test 
that would be in California. 
OYSTER-DRILL CONTROL 
By Dr. HENRY FEDERIGHI 
Any remarks that I might make must be, necessarily, fragmentary. I have 
been working on the problem for a little less than three months, and most 
of that time has been spent in getting a laboratory ready, playing the part of 
carpenter, plumber, etc.—everything but a biologist. Recently I started the 
experimental work. 
The oyster “drill” is a very important pest in the oyster industry. It is 
known that the drills have caused tremendous losses to the oyster business, but 
until recently the oyster drill had not entered the Chesapeake Bay—one of 
the largest centers of the oyster industry. The old literature contains some 
data on the drill. The older workers who made surveys would recommend 
that something be done to control the oyster drill. They found the drill in 
this locality and that locality. Florida is especially fortunate in having a 
specific drill of its own. The work is just beginning, of course, and so not 
much has been done on the problem. The only work I know of is that done by 
& man in the fisheries here—one named Pope—who, in 1911, made some experi- 
ments at Woods Hole. He worked especially on the reaction of the organism 
