No. 2303. RED SPIDERS OF AMERICA— McGREGOR. 679 



Plate 77. 



Tetranychus pacificus, new species. 



Fig. 1, collar trachea; fig. 2, foreleg viewed laterally; fig. 3, penis; fig. 4, tarsal ap- 

 pendages; fig. 5, palpus and its appendages. 



Pi-ate 78. 



Tetranychus sexmaculatus Riley. 



Pig. 1, left foreleg, viewed ventrally; fig. 2, tarsal appendages; fig. 3, eye comeae of 

 right side, viewed from above; fig. 4, outline of body to show six typical spots from 

 which the species derives its name; fig. 5, frontal and subfrontal bristles; fig. 6, pal- 

 pal appendages; fig. 7, collar trachea; fig. 8, penis. 



Plate 79. 



Showing variations of the penis of such species for which this structure is known. 



Pig. 1, Tetranychiis willammettei McGregor; fig. 2, T. oregonensis McGregor; fig. 3, 

 T. monticolus McGregor; fig. 4, T. flavus Ewing; fig. 5, T. sexmaculatus Riley; fig. 6, 

 T. weldoni Ewing; fig. 7, T. telarius Linnaeus^ fig. 8, T. althaeae von Hanstein; fig. 9, 

 T. borealis Ewing; fig. 10, T. ludeni Zacher; fig. 11, T. bimaculatus Harvey; fig. 12, 

 T. pacificus, new species; fig. 13, Paratctranychus unungvis Jacobi; fig. 14, P. pilosus 

 Canestrini and Fanzago; fig. 15, P. citri McGregor; fig. IG, P. pratensis Banks; fig. 17, 

 P. ilicis McGregor. 



(Figs. 1, 2, 3, 5, 11, 12, 15, and 17 drawn from type or authentic material by the 

 author; figs. 4, 6, 9, and IG drawn from Ewing's descriptions; fig. 7 drawn from Berlese's 

 figure; figs. 8, 13, and 14 after Triigardh; fig. 10 after Zacher). 



Plate 80. 



Work of Tetranychus bimaculatus Harvey on cotton leaves. 



Fig. 1, incipient attack resulting in a single local discoloration spot; fig. 2, 

 advanced work of red spiders resulting in the distortion and discoloration of 

 entire leaf and ultimate defoliation of plant. 



Plate 81. 

 Tetranychus bimaculatus Harvey. 

 Fig. 1, adult female (X 116); fig. 2, adult male (X 150). 



