258 Bulletin 144 



Trcatmejit. — For certain reasons it was determined to save these 

 shrubs of cornus and pyrus if it were possible, and by the advice of 

 Mr. Shngerland, who, it should be said, has rendered valuable assist- 

 ance in locating infested plants, noting the effects of sprays, etc., the 

 trunks and larger branches of the shrubs were treated with whale-oil 

 soap, dissolved in water at the rate of two pounds of soap to one 

 gallon of water. This has been much recommended, it being con- 

 sidered the most destructive to the scales of any insecticide which 

 could be used without injury to the host. Even this material will 

 injure foliage, so that it must be used when the plants are dormant or 

 else, as in the case in question, applied only to the trunks and larger 

 branches. It should be stated that the infested shrubs under treat- 

 ment had already leaved out when the scale v/as discovered. 



The effects of the whale-oil soap, thus applied, were all that could 

 be desired. No live scales could be found, after a lapse of several 

 days, where this solution had been applied. A few of the shrubs 

 which had been treated with a solution containing only half as much 

 soap as the above, that is, one pound to a gallon of water, still bore 

 live scales in considerable numbers. 



The whale-oil soap was applied about the first of May. Nothing 

 more was done for several weeks, but a careful watch was kept of the 

 condition of the scales, with the intention of treating them with kero- 

 sene when the proper time should arrive. In the meantime, numerous 

 experiments were made to determine how strong a mixture of kerosene 

 and water could be safely applied without injury to the foliage. The 

 result of this investigation indicated that a mixture of four parts of 

 water and one of kerosene could be used with little or no danger of 

 burning the foliage. 



Accordingly, on June 25, when the condition of the scales seemed to 

 indicate that the young insects were about to migrate, the shrubs were 

 thoroughly sprayed with a mixture of kerosene and water in the 

 strength indicated, that is, one volume kerosene to four of water. On 

 July 2, a second application of kerosene and water was made. Treat- 

 ment was now delayed for a time and on July 23, the shrubs were 

 very carefully examined by Mr. Slingerland and not a single living 

 scale was to be found. We felt encouraged. There seemed to be no 

 need of further attention, so the shrubs were left to themselves; but 

 the end was not yet. 



