Kinsey: Studies of Cynipidx 



135 



edges of third to last segments distinctly, closely pur ct ate, the last seg- 

 ment reticulate; sparsely hairy latero-basally ; the second segment cover- 

 ing slightly more than half of the area; abdomen about as long as high, 

 or slightly longer or shorter; the tibiae and tarsi darker, the hind tibiss 

 almost black ; wing veins not heavy, the first abscissa of the radius hardly 

 infuscated; areolet of moderate size to very large; cubitus not continu- 

 ous, or very faint toward the basalis; length 2.5-4.0 mm., averaging large. 



GALL. — Eather large, solid stem swelling. Polythalamous, with a 

 great many cells. The swelling elongate or globose to massive, distinct 

 but only moderately abrupt, solid, covered with normal bark, a some- 

 what distinct, smoother ring about the exit hole; internally very solid, 

 entirely woody, the larval cell distinctly lined but closely embedded. On 

 stems of all of the Pacific Coast black oaks. 



RANGE. — California, Oregon. Probably also Washington and 

 British Columbia, wherever black oaks occur. 



The insects of this species emerge early in the spring, in 

 February and March, earlier further south. The galls are 

 hard and solid, and I have not found them eaten into by birds 

 and mice as are the white oak species of Plagiotrichus. 



The three varieties described here are confined to black 

 oaks, each to a single species, all of the Pacific Coast black 

 oaks being affected. Probably several varieties occur on each 

 oak as it occurs in different faunal areas, but this has been 

 proved only for the agrifoUa varieties. This species is not so 

 radically different from Plagiotrichus chrysolepidicola, but 

 shows characters typical of the other black oak species of the 

 genus. Its intermediate nature may be due to the close rela- 

 tions, probably dating from more remote geologic ages, of the 

 black live oaks and the white live oaks of the Pacific Coast. I 

 have included coxH and asyimnetricus in this genus, even 

 tho they are not closely related to some other species, 

 mainly because suttonii nicely connects these more extreme 

 species. The species is very closely related to Plagiotrichus 

 perdens which occurs on two of the same oaks over much 

 the same territory. 



Plagiotrichus suttonii variety suttonii (Bassett) 



Cynips Q. Suttonii Bassett, 1881, Can. Ent., XIII, p. 54. 



Cynips suttonii Packard, 1881, U.S. Ent. Comm. Bull., VII, p. 57. Riley 

 (in Packard), 1890, 5th Pvpt. U.S. Ent. Comm., p. 115. 



Andricus (Callirhytis) Suttoni Mayr, Gen. Gallenbw. Cynip., p. 28. Ash- 

 mead, 1885, Trans. Amer. Ent. Soc, XII, p. 294. 



Callirhytis Suttonii Ashmead, 1895, Trans. Amer. Ent. Soc, XII, p. 304. 

 Ashmead (in Packard) 1890, 5th Rpt. U.S. Ent. Comm., p. 105. 



