4 BULLETIN 647, U. S. DEPARTMENT OF AGRICULTURE. 
characterizes the healthy orange tree, and production was far below 
the standard for trees of their average age. During the blossoming 
period the flowers were often somewhat too numerous and con- 
spicuous, a condition which characterizes a " sick " tree, and dying 
and dead trees were numerous throughout the district. 
The apparent cause of the diseased condition of the trees was 
often traced to heavy infestations by scale insects and white flies, 
but obviously, in some cases, other factors contributed to this condi- 
tion. Many orchards not invaded by ants exhibited the same symp- 
toms as those overrun by ants. Manifestly, the amount of injury 
done by the ant must be distinguished from that due to other causes, 
and this involves a knowledge of the general conditions characteriz- 
ing citrus culture in Louisiana. 
The investigation therefore was planned to cover, first, a thor- 
ough study of the habits of the Argentine ant in relation to orange 
trees, and, second, a study of the cultural practices and other condi- 
tions which might affect the successful raising of oranges in Lou- 
isiana. An experiment in the reclamation of an ant-invaded and 
practically abandoned orchard was conducted to determine what 
might be done in the way of making such orchards profitable. The 
problem of ant destruction and control in the* orchards was taken 
up at the beginning of the investigation and continued throughout 
its course. 
GENERAL ACCOUNT OF ORANGE CULTURE IN LOUISIANA. 
Louisiana is, perhaps, the oldest citrus-producing State in the 
Union. Orange trees have been cultivated there for at least 200 
years and, perhaps, longer, at least one introduction having been 
made from Cape Haitien (Cap Francois), Santo Domingo, by the 
original French concessionaires, who arrived in Louisiana in 1718, 1 
and it is probable that citrus trees had been grown there by the 
Spanish colonists previous to this introduction. 
During the long period that has elapsed since this introduction 
orange trees have suffered occasionally from severe freezes, and 
several times have been killed to the ground. Freezes of this ex- 
treme sort, occurring in the period from about 1718 to 1806, are 
mentioned by Le Page du Pratz, 2 Robin, 3 and several other writers. 
Similar killing freezes have occurred during the past century, one, in 
1835, killing every orange tree from the shores of the Atlantic to the 
Mississippi ; 4 others, the last one of which at least was equally dis- 
1 Le Page du Pratz. The History of Louisiana. Translated from the French of M. 
Le Page du Pratz, v. 2, p. 17-18. London, 1763. 
2 Op. cit., v. 2, p. 17. 
8 Op. cit , p. 474. 
*De Bow, J. D. B. In Review, v. 18, p. 609. New Orleans, 1855. 
