THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 57 



DEMONSTRATION IN IMPROVEMENT OF ANT-INVADED GROVES 



IN LOUISIANA. 



If preventing the Argentine ant from getting into the orange trees 

 would effect the practical commercial control of the chief armored 

 scales and the white fly in Louisiana, as it does that of the citrus 

 mealybugs in Los Angeles County, Cal., the problem of controlling 

 these insects would be simply one of getting rid of the ants. The 

 natural enemies of the principal pests of Louisiana, however, are 

 unable, even in the absence of ants, to prevent severe infestation. 

 On the other hand, if thorough measures of control were practiced 

 against these insects, there should be no reason to worry about the 

 ants. If the citrus mealybugs in California orange groves were as 

 thoroughly controlled by the regular fumigations as are the armored 

 and black scales, the ants could do only a negligible amount of harm 

 through these insects. 



DESCRIPTION OF DEMONSTRATION ORCHARD. 



The orchard reclamation work about to be described was conducted 

 on a grove at Ollie, La., practically abandoned, except for the har- 

 vesting of the crop. The grove consisted of about 1,055 sweet, naval, 

 mandarin, tangerine, and Jaffa trees, a block of 603 of which were 

 treated, the remaining 452 being left as checks. All the trees were 

 \ery thinly foliaged, with small tops, and many of them with mul- 

 tiple trunks. Many of the leaves were yellow and a moderate num- 

 ber of branches were dead. The trees were poorly shaped, and 

 branches were much tangled as a result of bad pruning. Many 

 of the trees were suffering badly with gummosis, 1 some being almost 

 completely girdled about the base of the trunk and larger roots by 

 this disease. (See PL III.) 



The ant infestation was as heavy as has ever been seen in any orchard. 

 All the trees were very badly infested with chaff, purple, and long 

 scales, the first named being exceptionally numerous. Almost all the 

 fruit had been very badly discolored by the rust mite every year, and, 

 in some years, infestations of the citrus white fly were also severe. 



The largest crop ever produced by the full orchard of 1,055 trees 

 was 1,400 boxes, occurring in the year 1911. The crop of the 1914 

 season had been only 400 boxes; or, in other words, the orchard had 

 suffered a crop reduction of 71.4 per cent in three years. 



TREATMENT OF THE ORCHARD. 



The demonstration work of improving this grove was started in 

 February, 1915, and continued until interrupted by the hurricane of 



1 Also called " sore shin " disease. 



