Bugs, Cicadas, Aphids, and Scale-insects 



over the leaf-surfaces, closing the breathing-pores (stomata) and thus truly 

 suffocating the plant. Although this scale species has been known for a 



century and a half, the males have 

 been seen but few times and in but 

 few places. Another familiar member 

 of this group, which secretes a distinct 

 white waxen egg-sac, is the maple- 

 scale, Pulmnaria innumerabihs (Fig. 

 255), common on maples in the 

 eastern states. 



Of the third group, that of the 

 most specialized (degenerate) scales, 

 the pernicious scale, already fully 

 described, may be taken as a shining 

 example. There is a host of these 

 armored scale-insects, and few trees or 



FIG. 255. 



FIG. 256. 



FIG. 255. The maple-scale, Pulvinaria innumerabilis. Females with egg-sacs on the 

 twig; young scales on under side of leaf, and a single young scale, much enlarged, 

 at left. (After Felt; natural size.) 



FIG. 256. Lecanium scales attacked by the fungus Cordyceps clavulata. (After Pettit; 

 much enlarged.) 



shrubs escape their attacks. The various genera are mostly distinguishable 

 by the shape of the covering scale, but to determine the species exactly 

 requires, for many, careful examination, under high powers of the microscope, 

 of the minute chitinous processes which form a fine fringe along the posterior 

 margin of the last abdominal segment. To make this examination it is 

 necessary to remove the female from under her scale, and mount her cleared 

 body flat in balsam or glycerine on a glass slide. An important species 

 in this group is the red orange-scale, Aspidiotus aurantii (Fig. 257), common 

 in orange-groves of southern California. A species very closely resembling 

 it is A. ficus, common in the Florida groves. On pine-needles one may 

 often note small, narrow elongate white waxen scales, with the smaller, 

 yellowish-brown exuviae at one end; these belong to the widely spread species 

 Chionaspis pinijolia. On apple-trees often occurs a roughened shining 



