218 ANNUAL EEPOETS OF DEPARTMENT OF AGEICULTUEE. 



preliminary observations, which, are being verified, that the burning 

 of the tops, which is an almost universal practice, destroys parasites 

 of the borer and thus removes a very important agency in holding the 

 pest in check. In fields where the tops had not been burned the 

 mfestation by the insect was found to be greatly lessened. Aii agent 

 was sent to Cuba to investigate the parasites of the moth borer in that 

 island. He succeeded in obtaming several species which do not occur 

 in Louisiana. One of them is now bemg propagated, but no pre- 

 diction as to the ultimate outcome can be made at this time. Tests 

 of the feasibility of controlling the borer m young cane plants by 

 the use of poisons were undertaken with successful results. 



Argentine ant. — The principal work on the Argentine ant dealt 

 with its relation to the sugar-cane mealy bug and with its control 

 under urban conditions. Experimental growths of sugar cane upon 

 which the mealy bug was planted showed that when the ant has 

 access, multiplication and spread are much more rapid than without 

 the access of the ant. The ant therefore has the efi^ect of causing 

 a pest of rather inconsiderable importance to assume a new role. In 

 the work of controlling the ant under urban conditions extensive 

 experiments were j)erformed in Hattiesburg, Miss. An especially 

 prepared poison mixture was exposed, mth the result that the 

 number of ants was greatly decreased. It now appears that the 

 perfection of this poison mixture supplies an economical and effective 

 means of controllmg this pest in cities. 



During the latter part of the summer of 1915 the ant was found 

 established at points in Georgia and North Carolina. A vigorous 

 campaign with the new sirup at Augusta, Ga., brought partial relief 

 within a few weeks. 



INVESTIGATIONS OF INSECTS AFFECTING THE HEALTH OF MAN. 



The work on insects affecting the health of man dealt with the 

 mosquitoes which transmit malaria and their control, with the house 

 fly, with the eradication of the Kocky Mountain spotted-fever tick, 

 and with the possible function of msects in the transmission of 

 pellagra. 



The work on malaria mosquitoes was conducted in Madison 

 Parish, La., on a large plantation where exceptional facihties for the 

 work were available. A study was made of the economic importance 

 of malaria and the loss to the planter resulting from invalidism due to 

 this disease. The study indicates that there is an annual loss of 

 about $6 per acre attributable to malaria. The work included studies 

 of the habits of the various species of mosq^uitoes which transmit the 

 disease and of methods of control. The mvestigation was assisted 

 greatly by Tulane University, and by the United States Bureau 

 of Fisheries, which placed an investigator m the field for the special 

 purpose of studying the top minnows which are important agencies 

 m. the reduction of the numbers of mosquitoes. 



The work on the house fly consisted of a contmuation of the 

 experiments of previous years in testing various compounds for the 

 destruction of the immature stages of the insect in stable manure. 

 This investigation was on a cooperative basis with the Bureaus of 

 Chemistry and Plant Industry. It was found that while borax will 

 undoubtedly be the most desirable agent for the destruction of the fly 



