THE HEMISPHERICAL SCALE. 



F^F> 



VlG.lS.— Tomocera californica, female. (Aft«r 

 Howard.) 



olece. It is, however, by uo means as abundant or injurious in that 

 State as in California. 



'^Xatural Enemies. — Enorraons quantities of the eggs of the black 

 scales are destroyed by tlie chalcid 

 parasite Tomocera calij'ornica, de- 

 scribed on p. [308] of this re- 

 port. [Fi.ii-. 17, male; Fig. 18, 

 female.] Particulars as to the 

 work ol this parasite are given at 

 the same jilace. 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 ajipear- 

 ance to tht- larvaj of the species of 

 DalTuma described in my last re- 

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

 more have been found siuce. 



" 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 ui)on the eggs 

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

 species of lady-bugs {CoccineUid(v)J^ 



THE HEMISPHERICAL SCALE. 



[Lecanium hemtHplicericnm Targioni.) 

 [Fig. 19.] 



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

 ure for 1880, p. 3;j4, thus treats of this Bark-louse: 



'■'■Adidt Female.— ^\\^\w. ai)proaching hemispherical with the edges 

 flattened. Average leugtii, 3.5™'"; width, 3""°; height, 2™™. The shape 

 and i)rop()rtions 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 .01""" 

 to .04"'"', and each cell contains a large granular nucleus. The anteniuB 

 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 iiulividnals in which this was 

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

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

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



