202 MAINE AGRICULTURAL EXPERIMENT STATION. I9TO. 



As stated under the discussions of colophoidea it is not cer- 

 tain whether ulmicola and colophoidea are distinct species or 

 dimorphic forms of the same species. Recognizing the danger 

 of making a composite species on insufficient basis, I have con- 

 sidered them distinct and think it expedient to do so unless they 

 are definitely proven to be the same, although I find no char- 

 acter except the venation to separate them, M being branched 

 for ulmicola and simple for colophoidea. 



Concerning the stability of the branched M for ulmicola the 

 following statements are of interest : 



Walsh, who first described the winged form, put the insect 

 in Thelaxes (M branched) and figured the Thelaxes wing with 

 a branched M. He says, "Dr. Fitch had not seen the winged 

 insect, of which I have obtained many specimens." Mr. Monell 

 erected Colopha (M branched) for this insect. In a letter to 

 Mr. J. J. Davis, December, 1908, Mr. Monell wrote : "I have 

 not seen the Colopha tdmicola for some years but have exam- 

 ined hundreds of specimens and find venation very constant. 

 I have also examined hundreds of Tetraneura colophoidea and 

 find its venation always constant." In a letter to me, February 

 3. 1910, Mr. Monell wrote: "Riley gave a whole summer to the 

 insect and published the results of his work in the Riley and 

 Monell paper. All this time the Tetraneura was unknown. 

 Riley's collecting point was, when he lived about 5 miles west 

 of Saint Louis, at Webster." 



Riley, who must have seen many winged specimens, records 

 (1879) only 5 specimens departing from Colopha venation. 

 "Wings as described by Walsh, the stigma being well rounded 

 and pale. (In three specimens examined, the third discoidal 

 (M) of the front wing is simple and precisely as in Pemphigus; 

 in one specimen, the first discoidal (A) is wanting on both front 

 wings, and in another the fork of third discoidal is wanting on 

 the left one." 



Thomas (III Report) describes M branched as did Walsh, 

 "the third (discoidal) obsolete at base, emits the fork almost 

 midway its length (counting to the imaginary point of inser- 

 tion)." 



Cowen (1895) records in a preliminary list of the Hemip- 

 tera of Colorado, as though it was exceptional, "Colopha ulmi- 



