GALL APHIDS OF THE ELM. 215 



by Mr. Monell dearly established the fact that graminis is cer- 

 tainly distinct from ulmi of Europe but not apparently different 

 from colophoidea, I wrote Mr, Sirrine, who very kindly sent 

 me slides of both the elm species recorded in 1893 and eluci- 

 dating notes. Extracts from Mr. Sirrine's letter February 28, 

 1910, read: 



"I am sending you half a dozen slides each of Tetraiieura ulmi 

 -graminis and Colopha ulmicola-eragrostidis. Both Tetraneura and 

 Colopha produce cockscomb galls on the elm, but those of Tetraneura 

 occurred on Ulmus amcricana while those of Colopha were on Ulmus 

 racemosa. One note states 'Colopha and Tetraneura occupy the same 

 kind of galls on elm. Are they dimorphic'? I found later that I had 

 apparently collected leaves of both Ulmus americana and racemosa with- 

 out distinguishing the difference. Furthermore I did not succeed in get- 

 ting Colopha to colonize on Lcersia virginica nor Tetraneura to colonize 

 on Bragrostis sp. From the specimens sent you will see that the most 

 constant distinction is the forking of the 3rd discoidal while the dis- 

 tance between the bases of the ist and 2nd discoidals, the lengths of 

 the antennae and body are less constant. Possibly the use of the name 

 Tetraneura ulmi for a species producing a cockscomb gall while the 

 Tetraneura ulmi DeGeer, described by Buckton produces a pedunculated 

 gall, may be confusing. The following is copied from notes : 'Colopha 

 uhnicola eragrostidis is lighter in color than Tetraneura ulmi graminis. 



The latter has abdomen olive green with yellow tinge due to body 

 contents, body linear throughout, thorax dusky instead of black. Colopha 

 abdomen yellow with reddish tinge, head and callosities black, remainder 

 of thorax yellow.' " 



In order to secure a safe basis for characterizing the wing 

 venation of this species 2,000 wings were examined of which 

 13 were abnormal in some respect. Sketches of these 13 wings 

 are given in figures 185-197, together with a sketch of a normal 

 wing (fig. 184). We had 1,000 specimens, 987 of which had 

 normal venation on both sides, the remaining 13 had normal 

 venation on one side. It will be noted that of the 2,000 wings, 

 i-,997 had M unbranched as is typical for Tetraneura. This 

 count was made from a haphazard collection of galls from 

 Ulmiis americana taken July 14, 1909, Orono, Maine, under the 

 aphid number 65-09. 



Bibliography. 



1883. Tetraneura graminis Monell. Can. Ent. 14: 16. Original descrip- 

 tion. 



1887. Tetraneura graminis. Oestlund Aphid. Minn. p. 24. 



1893. Tetraneura graminis. Osborn — Sirrine, Proc. la. Acad. Sci. 

 i: pt. 3. 100 (Ins. Life 5: p. 237.) 



