HEMIFTERA. 151 



2). This also infests oranges; but its injuries are overshadowed in 

 Florida by those of other scale-insects; A. nerii (Fig. 120) is the 

 common white scale, which occurs on a great variety of plants. It 

 is an imported insect; but I have collected it throughout our country 

 from the Great Lakes to the Gulf of Mexico, and from the Atlantic 

 to the Pacific; in the colder parts of the United States it is, next to 

 the mealy-bugs and Lecanium, the most common Coccid on house- 

 plants. In northern California, and especially in the Santa Clara 

 Valley, is found A. perniciosus; this is a circular, grayish scale which 

 infests nearly all of the deciduous fruit-trees grown in that State. It 

 is the most destructive of the scale-making Coccids; and before the 

 fruit-growers awoke to the importance of fighting it, it came near 

 destroying the orchards of that section. 



Didspis. — Our commonest representative of this genus is Didspis 

 rosiB (Plate VIII. 1); this is a snowy-white scale, which occurs 

 abundantly on neglected roses; I have found it also on raspberry, 

 and blackberry bushes. Didspis carueli (Plate VIII. 2) is common 

 in some localities on Juniper and allied plants. 



Chiondspis. — The common white scale of pear and apple is CJii- 

 onaspis fur/urns (Plate IX. 1). Another common species which 

 occurs throughout the United States upon the leaves of pine and 

 spruce is C. pinifolii (Plate IX. 2). C. eudnymi (Plate VIII. 3) in- 

 fests Euonymus ; it is remarkable for having the scale of the female 

 of a dirty blackish-brown color, instead of white, as is the rule in this 

 genus. The common white scale of willow is C. sdlicis. 



Mytildspis. — To this genus belong some of the best known Coc- 

 cids. Of those that occur on plants in the open air, only three 

 American species have been recognized. Two of these abound on 

 oranges. One of the orange species, M. gloverii, (Plate X. 2,) can be 

 easily recognized by the very narrow form of the scale, and the fact 

 that the eggs are laid in two rows beneath the scale ( Plate X. Fig. 2, c). 

 In the other orange species, M. citricola, (Plate X. I,) the scale of the 

 female is much wider, and the eggs are massed irregularly beneath 

 the scale. The Oyster-shell Park-louse of the Apple, M. pomdrum, 

 is distinguished from M. citricola only by minute characters. The 

 figure just referred to would serve equally well for this species, ex- 

 cept that it does not occur on the orange. It is the most common 

 scale of the apple in all parts of the United States in which that tree 

 grows ; it infests also a great variety of other plants. 



The food-plants of the species figured on Plate VII., and not 

 named above, are as follows: Parlatoria pergdndii Occurs on Florida 



