1:88 liEl'ORT OF THE DErARTMENT OF EXTOMOLOGY OF THIS 



III. OTHER TROMISING INSECTICIDES. 



The economic importance of scale insects as a group has re- 

 sulted in unusual efforts being made to develop methods for 

 their control. As a result various compounds are being devised 

 and tested from time to time with the hope of finding a cheaper 

 and more effectual way of combating these insects than any that 

 has yet been devised. Among the compounds that give promise 

 of success are the following: i 



Whale oil soap and crude petroleum cam pound. — Both whale oil 

 soap and crude petroleum are known to have great insecticidal 

 value and hence it would be supposed that a combination of the 

 two would give highly satisfactory results. The experiments 

 thus far, however, that have come to the writer's knowledge, 

 have not given altogether satisfactory results. A series of 

 experiments by Felt,^ gave no better results than he had ob- 

 tained with a plain 20 per ct. emulsion with water. In these 

 experiments, however, the emulsion was not used very strong 

 as but one pound of soap was used to each four gallons of water. 

 This was emulsified in a " kerowater " pump with a small 

 amount of oil, the pump being set to discharge but 10 per ct. of 

 crude peti'oleum. 



This compound is undoubtedly worthy of further experiment. 

 It is not improbable that a stronger emulsion would prove more 

 effectual. 



Lime, sulphur and salt wash. — This compound has been used 

 extensively and with much success in California. The prolonged 

 periods of dry weather characteristic of that country are espe- 

 cially favorable to the use of compounds of this kind. Experi- 

 ments with this insecticide in the East have not given very satis- 

 factory results as a rule. A prominent exception, however, is a 

 series of experiments by Marlatt, conducted at Washington, and 

 published in Bui. 30, N. S., U. S. Dept. Agr., Div. of Entomology, 

 pp. 84-3G, which gave very promising results. In explanation 

 of the unusual success of the treatment Dr. Marlatt states 



"Bulletin N. Y. State Museum, No. 46, Vol. 9, p. 337. 



