»» 



.lOUENAL OF AGRICULTURE OF P. K. 



former^ entomologists of the Insular Experiment Station, and by 

 former assistant entomologist Eugene G. Smyth. Mr. R. H. Van 

 Zwaluwenbnrg. entomologist of the Federal Experiment Station at 

 ^Mayagiiez. has also earried out work along this line, as is noted liero- 

 iifter. Credit is due to all of these workers for the data given below. 



Mr. Eugene G. Sm.vth. who has recently published an article^ 

 on the white grubs injuring sugar cane in Porto Rico, states that 

 ten distinct species of white grubs have been segregated and studied. 

 Of these, four belong to the genus Phyllophaga and one to the genus 

 Phytalus in the tribe Melolonthini, wliile the otlier five belong to 

 three genera in the tribe Dynastini. 



It was in connection witli the members of the genus I'liyllo/ihaya 

 that most of the experimental work was conducted and to which 

 the following data apply. 



The various experiments liave been grouped according to the fol- 

 lowing headings: soil fumigants, soil insecticides, mechanical iiictli- 

 ods, poison sprays, and parasitic insects and diseases. Space does 

 not permit the publication of all the experiments conducted in some 

 cases, so selections have been taken that represent tiie tj^pical results 

 obtained in each group. 



SOIL FUMIGANTS. 



Under this heading liave bcM'ii grouped tlie experimt-uts conducted 

 Avith carbon bisulphide, gasoline, tobacco extract, potassium cyanide, 

 and vaporite, since in all cases the gases or fumes given olT by these 

 substances were (i«^pended upon to kill the grubs. 



Carbon bisulphide. 



To test tlie value of carbon })isulphi(l<' as a killing agent. t<» dc- 

 tei'jiiine the best method of application, and the most etHicient amount 

 of the liquid to use, the two following experiments were made. J'hey 

 were conducted in cane land severelv infested with grubs.- 



* Journal of the Dept. of Agric. of P. R., Vol. 1, no. 2., pp. 47-92, no. 3, pp. 141-169. 



