Kinsey: Studies of Cynij)idse 



133 



EANGE. — California and Ore<^on. Probably wherever Quercw> 

 Kelloggii and Q. Wislizenii occar. 



This species in several i*espects represents a considerable 

 specialization for this genus. In no other species, as far as 

 I know the genus, does the larval cell drop out of the gall be- 

 fore the insect emerges. The species is directly related to 

 Plagiotrichus siittonii, which occurs on Pacific Coast black 

 oaks; the galls of the two are distinct. These galls are very 

 common on Querctis Kelloggii and Q. Wislizenii, but I am not 

 certain that they occur on the other black oak of the Pacific 

 Coast, Q. agri folia. A couple of galls I collected at Descanso, 

 California, on February 23, 1920, are recorded from agrifolia, 

 but I cannot be positive of this determination, especially since 

 the two oaks intergrade regularly in their southern range. 



As I noted before, these galls kill the stems beyond the 

 point of infestation, and thus kill the whole tree. Extensive 

 stands of young black oaks are sometimes badly hurt. 



I do not know when the insect matures ; emergence occurs 

 apparently after the larval cells drop to the ground. I found 

 old galls, with no fresh galls evident, from January in south- 

 ern California through April in Oregon. 



Plagiotrichus per dens variety per dens (Kinsey) 



Andricus perdeus Kinsey, 1922, Bull. Amer. Mus. Nat. Hist., XLVI, 

 p. 286, pi. XXIV, figs. 5-7. 



FEMALE. — Differs from the female of the other variety only in 

 having the foveae less Avide, distinctly separate, and in averaging some- 

 what larger in size, up to 3.0 mm. in length. 



GALL.— Differs from the gall of the other variety only in having 

 the bark more roughened, the splitting more ragged. On Quevcus Kel- 

 loggii. 



PvANGE.— California: Gilroy (Redwood School) (?), Placerville 

 (?), Redding (?), Santa Rosa (?), Ukiah (?). Oregon: Ashland, 

 Grants Pass, Roseburg. 



TYPES.— 2 females, 12 larval cells, and 26 infested twigs. Holotype 

 female and paratype galls at The American Museum of Natural His- 

 tory; paratype female and galls with the author; paratype galls at Stan- 

 ford University, the U.S. National Museum, the Museum of Comparative 

 Zoology, and the Philadelphia Academy. Labelled Ashland, Oregon; 

 April 6, 1920; Q. Kelloggii; Kinsey collector. 



This variety is very similar to the variety on Wislizenii, as 

 far as I can see differing only in the two characters described, 

 slight differences in galls, and the different host. Que reus 



