232 



elm leaf -beetle, or injury by the sugar maple borer Plagionotus 

 speciosus Say, prepare the way for the horntail larva. Ecologically 

 considered, the leaf -beetle and the borer initiate a succession of in- 

 sect invasions into the tree trunk; Tremex follows, with its parasite 

 Thalessa; and these in turn lead the way for still others; thus a suc- 

 cession of insects is produced. 



Cynipid^ 



Holcaspis globulus Fitch. (Oak Bullet Gall.) 



This gall was taken on white oak, Quercus alba, in the upland 

 forest (Sta. IV, a) Aug. 26 (No. 170). 



Consult Cook ('05) and Beutenmiiller ('04) for figures and de- 

 scriptions of various kinds of galls mentioned in this list. 



Amphibolips confluens Harr. (Oak-apple or May-apple Gall.) 



These galls were abundant upon the forest floor in the upland 

 Bates woods (Sta. IV, a) during August (No. loi). The galls grow 

 upon the leaves of several species of oaks (Quercus). 



Amphibolips prunus Walsh. (Acorn Plum Gall.) (PI. LXII, fig. 2.) 

 A single specimen of this gall was found on the slope of the south 

 ravine in Bates woods (Sta. IV, &) Aug. 22 (No. 131). Another 

 specimen came from the woods northeast of the Bates woods Aug. 

 20 (No. 96). It grows upon acorn cups. 



Andricus clavula Bass. (White Oak Club Gall.) (PI. LXII, fig. 5.) 



This gall, formed in the terminal bud, was common on white oak, 

 Quercus alba, in the upland Bates woods (Sta. IV, a) Aug. 26 (No. 

 170). 



Andricus cornigerus O. S. (Horned Knot Oak Gall.) (PI. LXII, 



fig- 3-) 

 This gall occurred in very large numbers on the branches of 

 shingle oak, Quercus imbricaria, in a forest just northeast of the 

 Bates woods, Aug. 20 (No. 96). The galls are old and apparently 

 decaying. 



Andricus lana Pitch. (Oak Wool Gall.) (PI. LXII, fig. 4.) 



Two examples of this gall were found on leaves of white oak, 

 Quercus alba: one was taken near the Bates woods (Sta. IV) Aug. 

 20 (No. 96), and the other was found in the Bates woods (Sta. IV, a) 

 on the petiole of a leaf, Aug. 26 (No. 170). 



Andricus seminator Harr. (Oak Seed-gall.) (PL LXIII, fig. i.) 



A single specimen of this gall was found upon Quercus ■ alba 

 (Sta. IV, a) Aug. 20 (No. iqi). The cotton-like masses of this 



