AKT. itt. GALLFLIES OF THE FAMILY CYNIPIDAE WELD. 15 



Kange in length of 200 measured specimens 2.45-4.2 mm. Average 

 3.45 mm. 



Type.—Cdit. No. 6420, U.S.N.M. Type and 39 paratypes. 



Paratypes also in Carnegie Museum, Pittsburgh, Pennsylvania, 

 and with United States Biological Survey. 



Host. — Quercus rubra Linnaeus, Quercus coccinea Muenchhausen, 

 and Quercus texana Buckley. 



Gall. — A stony mass of cells inside the acorn more or less filling 

 the interior and encroaching upon or obliterating the cotyledons. 

 They can not be separated at present from the galls of Callirhytis 

 frutlcola Ashmead, whose host source is in doubt. 



Ilahitaf. — The type locality is Ironton. Missouri. The Q. rubra 

 material was collected at Ironton on October 5, 1917, from a tree on 

 a steep ravine slope in the woods. The affected acorns are about full 

 size, but nearly black, and one can soon learn to distinguish them. 

 They drop before the normal acorns and they then contain larvae. 

 Adults emerged in breeding cage April 25, May 5, 10, 12, and 18, 

 1919, and more in 1920. These galls were seen in Q. rubra acorns at 

 Richmond and Wharton, Texas, and found once at Evanston, Illinois, 

 and at Bluemont. Virginia. 



About Chicago similar galls giving similar but smaller flies are 

 much more common in acorns of Q. coccinea. A large number of the 

 affected acorns of the 1916 crop were gathered at Evanston, Illinois, 

 on April 22, 1917, and two adults were cut out in September of that 

 year and more September 1, 1918. A lot issued May 5-18, 1919, and 

 more in 1920. As the coccinea acorns are smaller than those of Q. 

 mbra the cells are smaller and so are the flies. One hundred flies 

 from each source were measured with results as follows: From ruhra, 

 range 2.75-4.20, average 3.89 mm. ; from coccinea., range 2.45-3.60, 

 average 3.01 mm. Galls in coccinea. acorns have been seen at Win- 

 netka, Illinois ; Webster Groves, Missouri ; and at Ithaca, New York, 

 where on August 17 the red squirrels were opening the affected acorns 

 for the well-developed larvae and dropping the fragments on the 

 ground. 



Similar cells inside acorns of Q. texana were found October 25, 

 1917, at Boerne. Texas. Li^dng flies were cut out November 7, 1920. 

 Twelve of these average 3.34 mm. 



CALLIRHYTIS PETROSA, new species. 



Female. — Eeddish-brown, tips of antennae and posterior two- 

 thirds of abdomen infuscated. Head broader than thorax, cori- 

 aceous, seen from above axial line half width of head, facial .76 

 transfacial, clypeus slightly emarginate, interocular space .53 trans- 

 facial and area 1.25 times as broad as high, malar space .46 eye 



