PREFATORY NOTE. 
The following article by Mr. Johnson, one of the entomological 
assistants of the State Laboratory of N atural History, detailed for 
service in the office of the State Entomologist, contains in part 
results of work done by him as a graduate student of Stanford 
University before his connection with this institution, and written 
up as a thesis for the master’s degree. Much of his time has been 
given to the subject, however, since his engagement here, and a 
large part of the present paper is based upon results of this 
later work. 
Although the Mediterranean flour moth has not yet been found 
to infest any mills in this State, its distribution in oui \icinity 
f makes it practically certain that it will eventually appear within 
our limits, and a comprehensive article on it is consequently even 
more timely than it would be if withheld until aftei the thieatened 
invasion were an accomplished fact. 
It is of great consequence to every miller that he should be not 
only forewarned of his liability to serious annoyance and heavy 
loss by the work of this worst of the pests of the flouring mill, 
but that he should also be thoroughly forearmed with informa¬ 
tion as to the signs of its presence, the characteristics by which it 
may be unmistakably recognized, and the measures of prevention 
and destruction to be used against it. 
I have gladly availed myself, therefore, of this opportunity to 
put the millers of this State and of the country in possession of 
the essential facts, and to have compiled for the benefit of the 
working entomologist a complete review of the history and results 
of previous studies of this insect pest. 
S. A. Forbes. 
