by the noted epidemic of scale infection referred to b}^ Hubbard as 

 prevailing throughout the entire orange, lemon, and olive districts 

 along the shores of the Mediterranean from Italy to Spain during the 

 first decade of the present century, which later subsided ver}^ largely 

 of itself, efficient remedies at that date being practically unknown. 



In this country, scale infestation varies considerably from year to 

 year. The fluted scale, in California, increased enormousl}" during the 

 first ten or fifteen years and threatened the verj^ existence of the citrus 

 orchards. Thanks, however, to the Australian ladybird, and, doubtless 

 also to many native predaceous and parasitic insects-, it is no longer 

 feared in California. The long scale in Florida, also, was much more 

 injurious in the first years of its activity than it has been since. In 

 1896 the black scale was very abundant and destructive in the orange 

 districts about Riverside, Cal. Partly owing to adverse climatic con- 

 ditions and partl}^ to natural enemies, this insect has almost disappeared 

 from this district, which is now one of the least affected b}^ scale insects. 



These facts are cited to give the citrus grower whatever encourage- 

 ment they may offer, but not with the idea of belittling the need of 

 remedial operations. 



NATURE OF THE mJURY OCCASIONED BY SCALE INSECTS. 



The damage occasioned by scale insects is of several kinds. The 

 first and principal injury is the extraction of the juices of the plant, 

 the scale insect in its relation to its food plant being a mere pumping 

 machine, which is continuall}^ absorbing the sap from its host. While 

 the amount extracted by a single insect is very small, when multiplied 

 by millions it greatly weakens the plant. With some species the 

 excess is thrown off in the form of so-called "honey dew," which accu- 

 mulates in drops and spreads out over the bark or leaf as a sticky 

 liquid. This liquid attracts ants, which very often gives rise to the 

 erroneous belief that the ants are depredating on the plant. 



Another form of injury results from the honeydew excretion, which 

 not only prevents normal respiration, but develops a black fungus 

 covering the leaves, twigs, and fruit, and still further stifling the 

 plant and reducing the marketable value of its products. 



Associated with the damage due to the absorption of the juices of 

 the plant by the scale insect is a diseased condition, particularly to be 

 noted in the limbs, caused by the irritation excited by the beaks or by, 

 the injection of some poisonous liquid. 



The extreme injury by scale insects arises from the further fact that 

 they are active the year round in climates where citrus trees can be 

 grown. Their most rapid breeding period is from May to August, 

 but continues through October and November. In the winter or 

 rainy season they are more dormant and breeding is at a much 

 lessened rate. 



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