DESCRIPTION OF A NEW GALLFLY 131 



DESCRIPTION OF A NEW GALLFLY (ANDRICUS 

 DECIDUA) 



{Hymenoptera, Cynipids) 

 By WILLIAM BEUTENMULLER 



Andricus decidua, new species. 



Cynips q. decidua Bassetl, Proc. Ent. Soc. Phila., vol. iii, p. 689, 1864. 

 C^nips ? decidua Ashmead, Trans. Am. Ent. Soc, vol. xiv, p. 127, 1887. 

 Cynips decidua Felt, Ins. Affect. Park and Woodl. Trees, p. 627, 1906. 



Female : Head yellowish brown, vertex and posterior part blackish. 

 Antennae 1 4-jointed, basal joints brown, others much darker, long and 

 extending backward to the middle of the abdomen. Thorax jet black, 

 highly polished cind smooth, microscopically punctate on each side ante- 

 riorly. Parapsidal grooves sharp and deep, continuous, parcJlel, suddenly 

 converging at the scutellum where they are close together. Anterior 

 parallel lines very fine and short. Median line scarcely evident, except 

 by transmitted light. Lateral grooves fine and short. Collar and pleurae 

 punctate, the latter with a small, smooth, polished area. Scutellum black, 

 smooth and shining, gradually becoming rugose toward the apex from 

 beyond the middle, and with two large smooth foveas at the base, sepa- 

 rated by a very fine carina. The scutellum is narrowly margined and is 

 narrov/er at the base than apically. Abdomen compressed, sides slightly 

 rounded and sharply keeled above and below, sheath of ovipositor very 

 long, club-shaped and not extending beyond the shorter anal projection. 

 Legs pale yellowish brown. Wings hyaline ; radial area broad and 

 closed ; areolet small and triangular ; cubitus almost continuous. Length, 

 2 mm. 



Gall : On the midribs of the leaves of red oak (Quercus rubra) and 

 black oak (Q. celutina). Rounded or elongated swellings filled with 

 oblong kernels from a few to about 40, all depending upon the size of 

 the gall. When young these bodies are concealed in the hard, fleshy 

 part of the gall and as the swelling grows older the seed-like kernels 

 gradually protrude therefrom and when fully grown late in September 

 and early in October the swelling bursts open completely and the kernels 

 fall to the ground. The gall is green when fresh and the kernels are 

 whitish, yellowish, sometimes tinged cifter they become exposed. 



Habitat: New England States, Middle States, and southward to at 

 least North Carolina and westward. 



