ABT. 23 REVISION OF MACROCENTRUS MUESEBECK 15 



3. MACROCENTRUS CRAMBIVORUS Viereck 



Macrocentrus (Aniicroplus) crambivorus Viekeck, Proc. U. S. Nat. Mus., vol. 



40, p. 183, 1911. 

 Maorocentrns {Amicroplit^) plesius ViEatECK, Proc. U. S. Nat. Mus., vol. 44, p. 



556, 1913. (New synonymy.) 



Types. — In the United States National Museum. 



In his description of plesius, Viereck called attention to the similar- 

 ity of that species to crambworus, but apparently he did not appreci- 

 ate the extent to which variation occurs in species of Macrocentrus. 

 In my opinion the types of the two species are clearly conspecific, and 

 it may become necessary to suppress both names as synonj^ms of 

 crainhi Ashmead, but owing to the apparent constancy of certain 

 differences cramhivomis is for the present being held distinct. The 

 eyes in general are smaller than in crmnbi, and the cheeks and temples 

 correspondingly broader and less strongly receding, the malar space 

 longer, and the face slightly broader; the female antennae appear 

 constantly to have fewer segments, as noted in the key, and to be a 

 little darker in color; the male antennae are similar in the two 

 species, being usually 36 to 39 segmented with the flagellum entirely 

 brown, but the thorax of males of cranibivorus seems to be consist- 

 ently darker in color than in crmnhi; in general the lower abscissa of 

 basella, as compared with the upper abscissa, is relatively longer in 

 cranibivorus, but this difference is not dependable. 



The material examined includes, in addition to the type series of 

 cranibivorus and plesius, series in the national collections reared 

 from crambid larvae taken at Mount Jackson, Va., and Elmore, Ohio ; 

 three specimens obtained from Grambus hortuellus Hiibner at Ware- 

 ham, Mass.; another series reared from a Cramhus larva on corn, 

 locality not noted ; and collected specimens from Virginia, Massachu- 

 setts, Pennsylvania, District of Columbia, Georgia, Illinois, Iowa, 

 South Dakota, Colorado, and Canada; also a single specimen from 

 Michigan at the corn-borer laboratory, at Arlington, Mass.; and a 

 series of 12 specimens from Marthas Vineyard, Mass., in the collec- 

 tion of the Boston Society of Natural History. 



4. MACROCENTRUS CRAMBI (Ashmead) 



Amicroplus crambi Ashme.\d, Journ. Cincinnati Soe. Nat. Hist., vol. 17, p. 48, 1894. 



Type. — In the United States National Museum. 



The close relationship between this species and crambivorus has 

 been discussed above under the latter name. M. crambi is also some- 

 what similar to collaris (Spinola) Nees, which was designated by 

 Foerster as the type of his genus Amicroplus, but differs in its more 

 slender form, smaller head, and much longer ovipositor. 



