TWO NEW CAMBIUM MINERS (DIPTERA) 



By Charles T. GrEEnE, 



Specialist on Forest Diptera, Forest Insect Investigations, Bureau of Entomology, 



United States Department of Agriculture 



HISTORICAL REVIEW 



The two species of Agromyza discussed in this paper add two new 

 cambium miners to science. The larvse mine in the cambium of the 

 living tree, the mine leaving a scar known as a "pith-ray fleck." ^ The 

 mines are very much like those of Agromyza pruinosa Coq., the cambium 

 miner in river birch (Betula nigra). ^ One of the species was reared from 

 red maple (Acer rubrum) and the other from service berry, or shad- 

 bush (Amelanchier canadensis). Both of these species run to A. setosa 

 in the table of Agromyza by Malloch.^ 



A dipterous cambium miner was first reared in Europe in 1906 by 

 Nielsen,* and in 191 3 the author reared an American species.^ Later, in 

 1 91 5, another species was reared by Grossenbacher ^ which was rede- 

 scribed by Malloch the same year." 



CHARACTER OF TREES ATTACKED 



The trees attacked are apparently healthy, and infested ones can not 

 be detected by their outward appearance. The only way to detect the 

 larva is to remove the bark and expose the cambium, where at a glance 

 one can generally recognize the new galleries from the old ones, since 

 the new larval mines are only faintly darker than the living cambium, 

 whereas all the old work is generally brown. 



CAMBIUM MINER IN RED MAPLE^ 



DESCRIPTION 



ADULT 



Agromyza aceris, n. sp. 



Male and female. — Black; frons opaque black, reddish along upper edge of 

 lunule ; width of frons about one-half that of head ; orbits wide ; four orbital bristles 

 present, situated near inner edge of orbit; shiny around base of orbitals, a row of 

 microscopic hairs between eye margin and orbitals; ocellar triangle slightly indicated 



' Brown, H. p. pith-ray flecks in wood. U. S. Dept. Agr. Forest Serv. Circ. 215, is p., 6 pi. 1913. 

 References, p. 14-15. 



' Greene, C. T. the cambium miner in river birch. In Jour. Agr. Research, v. i, no. 6, p. 471-474, 

 pi. 60-61. I9I4- 



' Maixoch, J. R. A revision of the species of agromyza fallen, and cerodontha rondani. 

 (diptera.) /n Ann. Ent. Soc. Amer., v. 6, no. 3, p. 269-340, pi. 28-31. 1913. 



* Nielsen, J. C. zoologische studien tlsER die markflECkE. In Zool. Jahrb., Abt. System., Geogr. 

 U. Biol. Tiere, Bd. 23, Heft 6, p. 725-738, pi. 30. 1906. 



' Grossenbacher, J. G. MEDULLARY SPOTS AND THEIR CAUSE. In Bul. Torrey Bot. Club, v. 42, no. 4, 

 p. 227-239, pi. lo-ii. 1915. 



' Malloch, J. R. some additional records of chironomiDvS for Illinois and notes on other 

 ILLINOIS diptera. In Bul. III. State Lab. Nat. Hist., v. 11, art. 4, p. 349-350, pi. 84, fig. 8-11. 191s- 



Journal of Agricultural Research, Vol. X, No. 6 



Washington, D. C. Aug. 6, 191 7 



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100302"— 17 1 



