318 THE CANADIAN ENTOMOLOGIST 



4 times as long as preceding section. Food-plant unknown. 



Id auriceps Melander. 



15. Small species, 1.5-2 mm. in length; general colour shining 

 black, interfrontalia black ; orbits lemon yellow on upper half ; 

 apical half of femora yellow ; tibiee brownish yellow. Food- 

 plant unknown. Mass., D. C, Ind., Ill marginata Loew. 



Larger species, 2.5-3.5 mm. in length; general colour opaque 

 black, gray poUinose; interfrontalia and orbits largely or 

 entirely yellow; femora narrowly yellow at apices. Food- 

 plant unknown. Mont., Id., Wash., Col., 

 Maine (coloradensis Malloch) genualis Melander. 



OUR BIRCH SYMYDOBIUS DISTINCT FROM THE 

 EUROPEAN. (APHIDID.F:— HOM.) 



BY A. C. BAKER, WASHINGTON, D.C. 



In 1909 specimens of the oviparous female of a species of 

 Symydohius were collected from birch by the writer at Puslinch 

 Lake near Guelph, Ont. These were determined as ohlongus 

 Heyden. Dr. Edith M. Patch* found the same species in Maine 

 in 1908 and gave an excellent description and figures of it under 

 the name oblongus. Specimens collected in 1903 on Betula alba in 

 Minneapolis, Minn., presumably by Mr. Theo. Pergande, are now 

 in the collection of the Bureau of Entomology. A study of the 

 different specimens available has led the writer to conclude that 

 our American form is quite a distinct species. 



Specimens of 5. ohlongus taken in Petrograd by Chlodkovsky, 

 in Warsaw by Mordwilko, and in Brussels by Schouteden, all 

 agree in characters, and these are uniformly different from our 

 American species. 



In the alate form the most striking difference is met with in 

 the relative lengths of the antennal segments. This will be seen 

 from the following measurements of ohlongus as -compared with the 

 description of the American species given herewith. 



S. ohlongus III, 1.12 mm.; IV, 0.72 mm.; V, 0.528 mm.; 

 VI, (0.208 mm. -1-0.112 mm.). 



*Me. Agr. Exp. Sta., Bull. 181. 

 September, 1918 



