112 HATCH EXPERIMENT STATION. [Jan. 



number of broods of this insect, and the proper times at 

 which to spray the trees in order to obtain the best results. 

 The difference in seasons is of course a factor in the deter- 

 mination of these points, and renders it necessary that the 

 Avork be continued for a term of years before final results 

 can be obtained. 



The oyster-shell scale can easily be controlled by mild 

 sprays if these are applied at the right times, but two years 

 ago no one in Massachusetts seemed to know just that time. 

 In States but a short distance south this pest has two broods, 

 and it has been doubtful whether there were not two here 

 also. In order to determine these questions, careful obser- 

 vations have been made during the last two years, and must 

 be continued for several more in order to obtain reliable 

 results. 



For nearly three months of the year all the spare time 

 of the entomologists was devoted to the preparation of an 

 exhibit for the Louisiana Purchase Exposition, taking time 

 which could otherwise have been devoted to experimental 

 work. The nature and scope of this exhibit has been pre- 

 sented elsewhere, and need not be given here. 



During the colder months of the year experimental work 

 is practically impossible, and this time is made use of in 

 putting together the results of previous investigations, and 

 drawing conclusions from them ; in classifying and arrang- 

 ing the materials gathered and received during the summer : 

 in solving the more complex problems connected with cases 

 of injury difficult to reach and control by ordinary means ; 

 and in original investigations of various kinds. 



The correspondence with residents of the State requires a 

 larofe amount of time. In 1903 this was less than usual, 

 the reasons for it being considered in the last report. This 

 year it has resumed its normal quantity, about 1,500 in- 

 quiries having been received and answered by letter, or by 

 sending printed information on the topics concerned. 



Particular effort has been made to obtain samples of the 

 injuries caused by insects, these being often markedly char- 

 acteristic, and therefore of the greatest utility in a collection 

 so constantly referred to. 



