178 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



746 show that the average infestation is about 50 per cent of the 

 maximum, which roughly gives a loss of about 500 pounds of sugar 

 per acre on the area infested, which amounts to some 300,000 acres in 

 Louisiana alone. The total annual loss would thus be 150 million 

 pounds, valued during pre-war times at about $7,000,000. This means 

 that if the insect were controlled the Louisiana sugar planters would 

 make approximately that much more sugar every year, or about one- 

 fourth more than the average crop. There is also considerable damage 

 to corn in Louisiana and to corn and sugar cane in Texas and Florida 

 which has not been estimated. 



A system of control by the native egg parasite, Trichogramma minu- 

 turn, has already been found satisfactory to some extent. It has been 

 the custom on the plantations to burn the leaves of the sugar cane 

 plant which are left on the field after the stalks are cut and carried to 

 the mill. This burning probably results in killing vast numbers of 

 the egg parasite without a corresponding reduction in the numbers of 

 the moth borer. To prevent it, the plowing under of the leaves has 

 been tried for the past six years, a method of cultivation having been 

 perfected in cooperation with the Louisiana Sugar Experiment Station, 

 and it has been found that the infestation by the moth borer is never 

 increased by this operation but ma}^ be considerably reduced, while 

 the benefit to the soil is very marked. The cost of the additional 

 labor required has been estimated by plantation managers to be less 

 than one dollar per acre, and considering the fertilizing value of the 

 leaves it really amounts to nothing at all. 



By avoiding the destruction of beneficial insects and by adding one 

 or more larval and pupal parasites to the very efficient egg parasite 

 already present, it is believed possible ultimately to obtain a fair 

 degree of control. 



METHODS IN ENTOMOLOGICAL FIELD EXPERIMENTATION^ 



By W. P. Flint, C. F. Turner and J. J. Davis 



The accuracy and value of results from field experiments, whether 

 they be experiments in agronomy, in entomology or other agricultural 

 subjects, depend largely, and in most cases wholly on the accuracy 

 and reliability of the methods used in obtaining the data. 



The past year the writers have been associated in the Hessian fly 

 problem and have found it necessary to work out ways of obtaining 

 data and to check and recheck the various methods to determine the 

 most accurate and satisfactory from all standpoints. Although most 



1 Published by permission of the secretary of agriculture. 



