140 THE MONTHLY BULLETIN. 



repeated applications small infestations might be entirely eradicated. 

 It has also been learned that a repetition of small doses, one half to 

 three fourths or full schedule No. 1, have usually given as good results 

 with the least injury to the trees, as the excessive doses which were 

 thought to be the best in the first work done. In Ventura County the 

 writer obtained good results by using the three fourths schedule, No. 1 

 (potassium cyanide), making a second charge at the end of the first 

 hour, thus using two doses at hourly intervals, making the entire 

 exposure two hours. Mr. H. A. Weinland reports that he has had the 

 best results by the use of the one half schedule, No. 1 (sodium cyanide), 

 under the same system. He reports a slight damage to leaves and fruit, 

 but no serious results. 



Much has been said relative to the use of oiled tents in the control of 

 the mealy bug. Undoubtedly the oiled tent could be as successfully 

 used as the ordinary tent if the dosage were cut down proportionately, 

 but, due to the difficulty in handling the tents and their greater suscep- 

 tibility to tearing and wear, they do not seem to be satisfactory for this 

 work. Repeated experiments carried on in Ventura County in 1909- 

 1910 caused the Avriter to entirely drop the idea of procuring an air- 

 tight tent, because of the great damage done to the foliage of the tree, 

 Miien the ordinary fumigation dosage with the untreated tent appeared 

 to be giving as good, or nearly as good, killing results without the 

 accompanying injury to fruit and trees. 



Conclusions. 



In Ventura County, where the mealy bug has been under observation 

 for a number of years and where control work has been carried on cjuite 

 effectively, it is the general belief now among orcharclists and by County 

 Horticultural Commissioner R. S. Vaile as well, that the fumigation 

 ordinarily used against black scale and such other pests as are present in 

 the orchard will serve to keep the mealy bug in such control that it will 

 not be an economic factor in the growing of citrus fruits. It is recog- 

 nized, however, that under certain favorable conditions the meah^ bug 

 might increase more rapidly than these other pests, and that occasionally 

 a special fumigation or spraying might be necessary to maintain an 

 equilibrium. It is a fact that in the districts where fumigation has not 

 been practiced for a number of years the mealy bug has become the 

 worst, and in general where this method of fighting insect pests has been 

 adopted and continued regularly for some time, it has not been a serious 

 consideration. This is by no means a universal rule, for in some dis- 

 tricts where fumigation has been used for a good many years the mealy 

 bug continues to be a pest. This is not strange, however, when we 

 consider that the black scale, though recognized as easily controlled by 

 fumigation, promises always to be a pest in citrus orchards, unless other 

 than our present-day methods are employed. Why, then, should we not 

 expect that the mealy bug would occasionally share a like position ? 



The results of the discussion given at the convention at Ontario 

 plainly indicate that of the two methods, spraying and fumigation, the 

 latter is the more efficient and reliable and, though often unsatisfactory, 

 has usuallv given the best results. 



