June, '17] QUAYLE: COCCUS CITRICOLA AND C. HESPERIDUM 373 



sixteen thousand every twenty minutes, stopping between reels to 

 answer the stream of questions which the admiring multitudes of 

 freshmen will certainly be stirred to ask. As for the general public, — 

 a motor-driven machine, a few hundred thousand feet of film, covering 

 all lines of scientific investigation, farm and orchard management, 

 and you can take that long cherished — but seldom realized hope — a 

 real vacation. 



The following paper was read by title: 



SOME COMPARISONS OF COCCUS CITRICOLA AND C. 



HESPERIDUM^ 



By H. J. QuAYLE, University of California, Citrus. Experiment Station, Riverside, 



California 



Coccus citricola w^as described as a new species in 1914.2 Pqj. gQ^e 

 years previous to that time, this species of scale insect was confused 

 with C. hesperidum as well as with one or two other species. The 

 identity of the two species named is still a matter of doubt with 

 persons not familiar with them, and, in certain stages or without 

 ample material, their identity may not be plainly evident even to 

 those who have given the species some study. Nevertheless the 

 species in question are quite distinct, and it is the purpose of this 

 paper to point out some of the differences and also some of the simi- 

 larities. 



The most important morphological characters separating these 

 two species of scale insects are to be found in the antennae, both as 

 regards the number and the relative lengths of the joints. 



Hesperidum almost invariably has seven joints, while citricola, in 

 the great majority of cases, has eight joints. 



In seventy-eight specimens of citricola in which 139 antennae were 

 examined, there were three scales each with seven joints in one 

 antenna and eight in the other. In four scales there were seven 

 joints in both antennae, and in four others there were seven joints in 

 one antenna while the other antenna was not examined. The remain- 

 ing number, or sixty-seven, had eight joints in both antennce. 



In seventy-three specimens of hesperidum examined all had seven 

 joints. 



iPaper No. 42, University of California, Graduate School of Tropical Agriculture 

 and Citrus Experiment Station, Riverside, California. 



^Campbell, Roy E. A new species of Coccid infesting citrus trees in California. 

 Entomological News 25: 222-224, 1914. 



