THE HEMISPHERICAL SCALE. 



Pio.18. Tomocera calif or nica, female. (After 

 Howard.) 



olece. It is, however, by no means as abundant or injurious in that 

 State as in California. 



"Natural Enemies. Enormous quantities of the eggs of the black 

 scales are destroyed by the chalcid 

 parasite Tomoiera californica, de- 

 scribed on p. [368J of this re- 

 port. [Fig. 17, male; Fig. 18, 

 female.] Particulars as to the 

 work of this parasite are given at 

 the same place. Upon one occa- 

 sion (August 25, 1880), I found 

 within the body of a full-grown 

 female a lepidopterous larva, 

 which was very similar in appear- 

 ance to the'liirvse of the species of 

 Dakruma described in my last re- 

 port as destroying bark-lice. The specimen, however, was lost, and no 

 more have been found since. 



u A number of beetles of the genus Latridius were found under scales 

 which had been punctured by the Tomocera, but probably would not 

 destroy the live insect. Many mites were found feeding upon the eggs 

 and young. The infested trees were also swarming with the different 

 species of lady-bugs ( Coccinellidce)." 



THE HEMISPHERICAL SCALE. 



(Lecanium hemisphcericum Targioni.) 

 [Fig. 19.] 



Professor Comstock, in the Report of the Commissioner of Agricult- 

 ure for 1880, p. 334, thus treats of this Bark-louse : 



"Adult Female. Shape approaching hemispherical with the edges 

 flattened. Average length, 3.5 mm ; width, 3 mm ; height, 2 mm . The shape 

 and proportions vary somewhat according as the scale is formed upon 

 a leaf or a twig. Upon the rounded twig it loses something of its hem- 

 ispherical form, becomes more elongated, and its flattened edges are 

 bent downwards, clasping the twig. In such cases, of course, its height 

 becomes greater and its width less. The color varies from a very light 

 brown when young to a dark brown, occasionally slightly tinged with 

 reddish when old. The oval cells of the skin vary in length from .Ol mm 

 to .04 mm , and each cell contains a large granular nucleus. The antenuje 

 are 8-jointed with joints 1 and 2 short and thick; joint 3 is the longest, 

 and the succeeding joints decrease gradually in length to joint 8, which 

 is longer than the preceding. Occasionally a specimen is found in which 

 joint 5 is longer than 4, and I have seen individuals in which this was 

 the case with one of the anteuua3 while the other was normal. The 

 legs are long and rather slender; the bristle on the trochauter is long; 

 the articulation of the tarsi is very well marked. (This fact has sag- 



