THE COCCIDAE OF SOUTHWESTERN UNITED STATES 



49 



In all the available individuals of the second stage the derm had be- 

 come heavily chitinized, rendering them difficult to study. As far as 

 may be ascertained the pygidium in this stage differs but little from that 

 of the adult. 



First stage as in P. tridentata. 



Notes: It is this species that most closely resembles P. anomala Green. 

 Were it not for its discovery P. tridentata might well have been made the type 

 of a new genus. 



Genus DIASPIS Costa. 



"Diaspis" arizonica Ckll. 



Fig. 24. 



Type host and locality. From Prosopis velutina, several miles west 

 of Phoenix, Ariz. 



Material examined. From type host at Tucson, Ariz. 



Scale. Scale of the female white, flattish, with the exuviae subcen- 

 tral. Ventral scale quite thick. Scale of the male white, slightly elongate, 

 with the exuvium toward one end. Both male and female scales are 

 found in cracks in the bark. 



Fig. 24. "Diaspis" arisonica Ckll. : pygidium. 



Adult female with the anterior portion of the body quite heavily chi- 

 tinized, the abdomen, except for the pygidium, membranous. Pygidium 

 heavily chitinized, its surface presenting a wrinkled appearance. There 

 are no plates. Three pairs of lobes present, these scarcely distinguish- 



