Attack by Larvacides 1 77 



4. Simplicity of composition. The manu- 

 facture of this larvacide requires neither compli- 

 cated apparatus nor highly skilled labor. 



5.. Low toxicity to higher animals. It is 

 practically harmless in ordinary dosage or in 

 dilution to cattle, poultry, etc. 



6. Rapidity of toxic action. When used in the 

 field, it killed all Anopheles larvje and pupae in 

 ten to twenty minutes. 



7. Cheapness of the product. In Panama, the 

 cost is about eighteen cents a gallon. 



8. Absence of danger from fire. The con- 

 centrated larvacide is inflammable, but not easily 

 ignited. In dilution it is not inflammable. 



9. It is useful in the rapid determination of 

 the presence of mosquito larvae and kills those 

 at rest embedded in the mud. 



ID. In addition to its toxicity for mosquito 

 larvae the phenol-resin larvacide is also highly 

 toxic to protozoa and algae, as well as most of the 

 varieties of the common grasses encountered in 

 Panama. The algacidal and herbicidal properties 

 of this larvacide are of frequent use in mosquito 

 eradication. 



The disadvantages of this larvacide are : 

 I. It does not emulsify and is inert in brackish 

 water. This is a serious disadvantage because 



