114 INSECTS AFFECTING VEGETATION 



velopment of the different species in this group is very similar, in 

 that they all retain the power of locomotion until nearly the end of 

 their lives, and do not suffer the loss of limbs and the marked retro- 

 grade development already described in the case of the armored 

 scales. They excrete liberally the honeydew, which is followed by 

 the smut fungus. In this group are included some of the worst scale 

 pests of the orange and lemon, notably the black scale, the fluted 

 scale, and the mealy bug. Not being so firmly attached nor so pro- 

 tected by a covering shell or scale, they are as a rule more easily de- 

 stroyed by fumigation or sprays, and they fall a more ready prey to 

 attacks of predaceous and parasitic insects. All of the species are egg- 

 laying. Their Lecaniums and wax scales deposit their eggs in cavi- 

 ties under their bodies, formed by the contraction of the female in- 

 sects, so that ultimately the mothers become mere shells over vast 

 numbers of eggs and hatching young. The mealy bugs and fluted 

 scale excrete a quantity of cottony fibers, which are stocked. with 

 eggs. After a certain amount of incubation, the young hatch and 

 escape from beneath the old parent scales or burrow out of their cot- 

 tony nests. In transformations and general life history, except in 

 the points noted, these scale insects closely duplicate the habits of the 

 armored scales. 



The Black Scale, This scale insect is notably an olive pest, but 

 it also attacks citrus fruits, and is quite as destructive to the latter as 

 to the olive. It is an insect of world- wide distribution, having been 

 an important enemy of the olive and citrus fruits in the Old World 

 as far back as we have any records. It also affects a great variety of 

 other fruits and plants. It occurs more or less in greenhouses, and 

 has undoubtedly been transported to various parts of the world upon 

 greenhouse plants as well as upon the various subtropical fruits. In 

 the United States it is especially destructive only on the Pacific coast, 

 and while it occurs generally in Florida it has never there assumed 

 any great importance as an enemy of the orange or lemon. It not 

 only saps the vitality of the plants by the extraction of their juices, 

 but also abundantly secretes honeydew, which results in a badly at- 

 tacked plant becoming thoroughly coated and blackened with the 

 sooty fungus. 



The adult insect is dark brown, nearly black, in color. Its char- 

 acteristic features are the one longitudinal and the two transverse 

 ridges. Very often the portion of the longitudinal ridge between the 

 two transverse ridges is more prominent than elsewhere, giving a 

 resemblance in these ridges to a capital letter H. The general sur- 

 face of the body of this scale insect is shagreened or roughened, which 

 will distinguish it readily, under a hand lens, from the allied spe- 

 cies, even before the ridges have become prominent. Very fortu- 

 nately for the citrus grower, the development of this insect is slow, 

 and it has but one brood annually. The young, however, appear over 

 a very wide interval of time, and this gives the appearance of more 

 than one brood. 



On reaching full growth, early in the summer, the female insect 

 deposits her eggs beneath her already much-hardened parchment- 



