86 MISC. PUBLICATION 17 4, U.S. DEPT. OF AGEICULTURE 



Its life history is not known to the writer, but it is believed to be 

 a primary solitary parasite which feeds externally upon the host 

 larva within the puparium or flaxseed and emerges therefrom as an 

 adult. 



DISTRIBUTION 



As may be seen from the foregoing records, this species has been 

 found in California, Oregon, Washington, North Dakota, Iowa, 

 Missouri, and Michigan. It seems to be common in all these States 

 except Missouri and Iowa. Apparently it does not occur in Europe. 



Some features of the distribution of this species are worthy of 

 special note. Perhaps the most interesting is the fact that where 

 it is commonest E. fulvipes appears to be either absent or rare, and 

 where E. fulvipes is most plentiful E. americanus is seemingly rare 

 or absent. The two species overlap to some extent, both being pres- 

 ent along the northern border of the United States from Oregon to 

 Michigan. In California E. americanus alone is present ; in Oregon 

 americanus is apparently common and fulvipes rare; in North Da- 

 kota and Michigan the two seem to be about equally common; in 

 Iowa and Missouri fulvipes is the common species and americanus 

 apparently uncommon, while east of the Mississippi River, except in 

 Michigan, americanus does not occur in the material studied. Con- 

 sidering this distribution in conjunction with the close relationship 

 of the two species and the great variability exhibited by both, one is 

 led to wonder whether, after all, the supposed specific differences are 

 really anything more than extremes of variations brought about by 

 climatic influences which tend to shorten or lengthen the develop- 

 mental period. Only careful breeding experiments can settle this 

 question. 



IMPORTANCE 



In California and throughout the northern tier of States from 

 Michigan to Oregon this parasite apparently is of considerable im- 

 portance, if one may judge by the frequency with which it is col- 

 lected. Not enough is known of it, however, to form much of an 

 idea of its relative value in control of the hessian fly as compared 

 to the other and better-known species. 



EUPTEROMALUS MICROPTERUS (Lindeman) 



Merisus intermedins var. mioroptera Lindeman, Bui. Soc. Imp. Nat. Moscou 

 (2) 1:182, 1887; Ormerod, Entomologist 20:317, 1887. 



Baeotomus coxalis Ashmead, Psyche 8 : 83, 1897 ; Marchal, Ann. Soc. Ent. 

 France 66 : 83, 1897. 



Eupteromalus arvensis Kurdjumov, Messager Ent. [Kiev] 2 : 3, 1913 ; Znamen- 

 ski, Poltava Agr. Expt. Sta., Ent. Dept. Bui. 2, 1923 (abstract in Rev. Appl. Ent. 

 (A) 12: 291, 1924) ; Meyer, Rpt. Appl. Ent. Lenigrad 4: 241, 1929. 



Meraporus gramdnicola Blunck (Mersius intermedins var. micropterus\ Linde- 

 man and Baeotomus coxalis in synonymy of) , Ztschr. Angew. Ent. 18 : 588, 1931. 



DESCRIPTION 



Eupteromalus rmcropterus is very similar to E. fulvipes in habitus 

 and in most details, but it may be distinguished by the following 

 characteristics : 



Female. — Very slightly more robust than in fulvipes; head thinner than in 

 fulvipes, about three times as broad as thick antero-posteriorly ; viewed from in 

 front the width to the height is in about the ratio 30 to 24; postocellar line 



