NOTES ON CEROCOCCUS. 



BY ROSE W. PATTERSON. 



Plates XXII-XXIV. 



Among the most injurious insects found upon the oaks 

 west of the Rocky Mountains are those scale insects belong- 

 ing to the genus Cerococcus. But three species of this 

 genus have thus far been observed and described: viz., 

 Cerococcus qiiercus Comst.^ C . ehrhorni Ckll.^, and C . cor- 

 ticis Town.^ 



The published accounts of these interesting coccids are 

 limited to brief descriptions of the adult females. In each 

 species the female lives within a case formed of waxy- 

 secretion. She is apodous, has single-jointed antennas 

 bearing stiff spines, and the terminal segment of her abdo- 

 men is prolonged into two lobes. Spinnerets of two kinds, 

 single and double, occur. The mentum is two-segmented. 

 Practically nothing descriptive of the immature stages or of 

 the general biology of the insects has been published. As 

 two of the species are common on the oaks of California, 

 I have had opportunity to observe something of the life- 

 history of these two forms, and the following notes include 

 the results of this study. This paper was prepared in the 

 Entomological Laboratory of Stanford University, under 

 the direction of Professor V. L. Kellogg. 



Cerococcus ehrhorni Ckll. 



Plate XXII, Figs. 1-9; Plate XXIV, A. 



This species was first found on the live-oaks in the 

 vicinity of Mountain View, California by Mr. E. M. Ehr- 

 horn, and was described by Prof essor T. D. A. Cockerell in 



1 U. S. Agric. Report 1881-1882, pp. 213, 214. 



2 "Psyche," Vol. VII, 1895, p. 255. 



3 Journal N. Y. Entom. See, Vol. VI, 1898, p. 170. 



[387 J May 4, 1901. 



'm 111901I 



