20 BULLETIN 647, U. S. DEPARTMENT OF AGRICULTURE. 



cultivation and pruning received by the trees. There was no ap- 

 parent difference between the two sets of trees as to abundance of 

 armored scales. 



RELATIONS WITH THE SOFT SCALES. 



Status of the Soft Scales of Citbus in Louisiana. 



Only four of the six principal citrus-infesting species of soft scales 

 occurring in Louisiana have been discovered in the orange section 

 of Plaquemines Parish. These are the soft brown scale {Coccus 

 hesperidum L.), the citrus mealybug {Pseudo coccus citri Bisso), the 

 Florida wax scale (Ceroplastes floridensis Comst.), and the barnacle 

 scale (C. cirripediformis Comst.). No injury to citrus, serious or 

 slight, ever has been attributed to the last two scales in the history of 

 the orange industry in the United States, nor do they now cause 

 noticeable injury to citrus in Louisiana. The first two are the only 

 citrus soft scales occurring in sufficient numbers in the orange groves 

 to attract attention. 



Morgan 1 states that the citrus mealybug was very abundant in 

 some of the orchards of Louisiana in 1893, especially in those well 

 protected from winds and in thick-growing trees such as the man- 

 darin, but was not a particularly serious pest at that time. These 

 statements apply equally well for all practical purposes at present. 

 The mealybugs occur scatteringly throughout the groves of Plaque- 

 mines, St. Bernard, and Orleans Parishes. They usually make a 

 strong start in the spring and early summer and threaten seriously 

 to infest certain orchards, but between the middle of June and the 

 first of August they are brought under control by their natural ene- 

 mies. Infestation goes the same course on fig trees in yards in New 

 Orleans, except that the mealybugs are at times somewhat slower in 

 being subdued there than in the orange groves. 



Regarding the soft brown scale, Morgan's statement that "it ap- 

 pears and disappears, being kept in check by parasites, and for this 

 reason has not attracted the attention of the orange growers " 2 also 

 applies to-day. Its status is still essentially the same, though it is 

 undoubtedly true that this scale will now be found in larger groups, 

 in places, because of abundant attendance by the Argentine ant. It 

 occurs upon nearly every budded orange tree over 3 years of age in 

 the State, and also on banana, rose, and loquat in the orange groves. 

 The important thing is, however, that it does not cause death or seri- 

 ous injury even to the twigs which it inhabits, does not blemish the 

 fruit, and is not of noteworthy economic importance even in orchards 

 overrun by ant.-:. 



*Op. cit., p. 69. *Ibid., p. 68. 



