THE SMALL-MAMMAL PROBLEM 741 
Where rats are very numerous, apply twelve months of intense 
slaughter, which will bring the problem within manageable 
limits ; then apply the Rodier system. Its great merit is the 
lengthy period of neglect that an area well in hand can sustain 
before becoming, if it ever does become again, a nuisance; its 
defect is solely the difficulty of execution. Rat-poisoning must 
cease, and rat-killing as a sport must be banned, though a 
careful man may shoot with safety rats carrying food, as the 
does alone perform this duty.” 
Mr E. Read, chief of the Rats Branch of the Ministry of 
Agriculture and Fisheries, has been kind enough to inform 
us of a method, discovered by the work of his department, 
by which the Rodier system can be applied in a practical 
and wholesale manner, without the initial trouble of capturing 
the rats alive and determining the sexes. During the earlier 
winter months, ¢.g., November, poisoning with a preparation 
of liquid extract of squill and milk has been resorted to, and 
many thousands of rats have been killed in all parts of the 
country by this means. Of the total number killed in this 
way at this season, no fewer than 85 per cent. were females, 
the milk proving to be an irresistible bait for the does nursing 
families at the onset of the inclement season. The Rodier 
system deliberately and generally applied could show no better 
result than this, because even with it, accident and error in 
the determination of sex would certainly lead to the death of 
many males. From this experience it would appear that active 
rat destruction should take place chiefly in the winter months 
when the does are hard pressed; the other months should be 
used chiefly for preventive work such as rat-proofing. 
Scientific study confers a measure of foresight, and it is 
often possible to predict many of the consequences which 
must flow from current actions. The small-mammal problem 
is one of the things pre-eminently susceptible to treatment by 
intelligent anticipation, and with our knowledge and experi- 
ence, we certainly ought not to be content with merely devising 
expedients to cope with the difficulties of to-day, heedless of the 
perils of to-morrow. Given sufficient determination, money, 
and patience, we might, in the course of time, succeed in 
exterminating both species of rat and the House Mouse in 
