IIYMEXOPTKROUS PARASITES. 1899 



which I made having failed. The importance of the introduction of 

 this, one of tiie commonest parasites of Picris rapae in Europe, and the 

 interest attaching to it justified the trial. But for the last few years I have 

 received many specimens, particularly from different parts of this country, 

 of a Microgaster bred from Pieris rapae which bore a suspicious resem- 

 blance to the European glomeratus. The material before me includes, 1st : 

 (from Europe) a perfect female which was received in 1879 by Mr. How- 

 ard from Dr. Gustav !Mayr of Vienna ; a large series in my own collec- 

 tion in the National Museum reared from the cocoons received from ^Ir. 

 Bignoll from England ; other specimens descended from these las^t and 

 reared in the District of Columbia, and two bunches of cocoons from Mr. 

 Scudder collected in Europe in 1872 ; 2d : (reared from Pieris rapae in the 

 United States) specimens from Prof. J. A. Lintner of Albany, N. Y., ]Mr. 

 G. Haley of Brownfield, Me., Mr. E. W. Allis of Adrian, Mich., Prof. 

 A. J. Cook of Lansing, Mich, and Mr. W. B. Alwood of Columbus, O., 

 and finally four authoritative specimens of Microgastcr pieridis (Pack.). 



A careful study of all these specimens makes it impossible to separate the 

 American bred forms from the European, from which fact it would seem 

 evident that other importations must have taken place of late years besides 

 that purposely made which I have already referred to. Indeed, as we 

 shall see in considering the common and wide-spread congregatus (Say), 

 one would be perfectly justified in looking upon it as an American repre- 

 sentative of glomeratus, and while its different habit, and the slight differ- 

 ences which I point out make it possible and desirable to keep them under 

 distinct specific names, yet the differences might with perhaps equal pro- 

 priety be regarded as varietal, especially as atalantae is intermediate be- 

 tween them. 



Thus it becomes in a measure a matter of mere speculation as to whether 

 the more typical glomeratus in America is an entomophagic derivative of 

 congregatus modified from breeding again in Pieris rapae or whether it 

 represents earlier importations from Europe. We must not wonder at this 

 difficulty in separating specifically allied European and American insects, 

 when zoologists are yet discussing the specific relations of many of the 

 higher animals common to both countries, and opinions differ among the 

 most competent to express them. In this country glomeratus, so far as 

 the material indicates, is confined to P. rapae, while in Europe it is reared 

 not only from the larva of this butterfly, but also from that of Mancipiura 

 brassicae and other species. 



Length of body, $,2.6 — 3 mm. Color black. Pilosity of head and thorax quite 

 marked and white. Head with the punctation very fine, tolerably dense, but less so 

 on the polished face and clypeus ; a deep puncture or fovea each side at apex of the 

 clypeus ; face xcith two more or less well defined, slender carinae diverging from the hnseof 

 the antennae fonoard , the space between them generally depressed, and in some cases short 

 striae diverging from the carinae; eyes brown; mandibles either pale brownish or 



