THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 7 



array of spraying machinery that was even more diversified and 

 inefficient than the insecticides. About 6.5 per cent of those who 

 reported had at one time or another treated for the white fly by 

 spraying the spores of the three or four entomophagous fungi known 

 to attack this insect. 



After becoming familiar with the relations of the Argentine ant 

 to the trees and the infesting scale and other insects, the history of 

 the plantings, the natural conditions, and the widespread neglect of 

 good cultural practices, one is forced to conclude that the latter are 

 factors of much greater importance than the ant as causes of damage 

 to and the destruction of citrus trees in Louisiana. The progressive 

 decrease of production occurring in the last five or six years, 1 as well 

 as most of the more severe forms of injury to the trees, is due to a 

 combination of the causes here enumerated. The several armored 

 scales, the white fly, and the rust mite, which, of course, cause much 

 injury to the trees, can be controlled without difficulty in the presence 

 of the ants and regardless of them, as will be shown later. It is pos- 

 sible that under new conditions the citrus mealybug and the fluted 

 scale may become serious pests in the orange groves of Louisiana. 

 The mealybug might become abundant on trees kept clean of other 

 scales and white flies or in the event of a scourge overtaking its 

 natural enemies. The fluted scale, from all reports, already has 

 become a serious pest to ornamental orange and other trees in the city 

 of New Orleans since the present investigation was discontinued, and 

 later may be expected to infest the orange groves. 



DISTRIBUTION OF THE ANT IN THE ORANGE GROVES OF THE 



UNITED STATES. 



LOUISIANA. 



Data on the distribution of the Argentine ant in the orange groves 

 of Louisiana have been received from the owners or by actual in- 

 spection of 99 per cent of the groves of the State. The ants are 

 present in 26.1 per cent, or about one-fourth of these groves. On 

 the west bank of the Mississippi River, from McDonoughville to 

 Home Place, in Plaquemines Parish, the ants are in 62.9 per cent 

 of the groves; from Home Place to Buras, exclusive of the latter, 

 they are present in 77.3 per cent of the orchards; from Buras to 

 Venice, inclusive, they have invaded only 5.5 per cent. On the east 

 bank of the river, in Orleans, St. Bernard, and Plaquemines Parishes, 

 23.8 per cent of the orchards between New Orleans and Olga, La., 

 are infested with the Argentine ant. Over 95 per cent of the citrus 



1 The actual reduction of the orange crop of Louisiana, based on complete data as to 

 number of bearing trees and amounts of greatest and last (i. e., 1914) crops of 80 per 

 cent of the bearing trees of the State, is 36.8 per cent. The present production, in other 

 words, is only 63.2 per cent of what the orange trees have proved themselves capable of 

 producing. 



