172 MAINE AGRICULTURAL EXPERIMENT STATION. 1917. 



only a little discolored above the base of the basal joint; the second, third, 

 and fourth abdominal segments have black hind-margins which occupy 

 about one-fifth of each segment, and the inner hind corners of the orange 

 spots are more rounded than in the male, but less than in the female of P. 

 fulviventris. Frons broad, being at the vertex about one-third the width 

 of the head; it is shining blue-black there, but the side dust spots are so 

 large as to leave only an indistinct middle line connecting to the indistinct 

 shining black space above the antennae ; the pubescence on the upper half 

 of the frons is partly black. 

 "Length about 8 mm." 



This species is much commoner in Maine than P. quadratus, 

 being represented in the collections by about 50 males and an 

 equal number of females. Especial abundance was noted at Oro- 

 no the tenth and eleventh of August, 1915 and the thirteenth 

 to the eighteenth of June, 1917. Other dates for Orono are July 

 31, Aug. 1, 6, 12, 15, 16, 19, and 25. Specimens were also taken 

 at Fort Kent, July 5 and 6, Presque Isle, July 8, and Bar Harbor, 

 July 25. 



The adults are commonest in tall grass, seeming to show a 

 preference for the proximity of open ditches where they hover 

 about, alighting frequently on the grass blades or spikes, males 

 as well as females teetering up and down with the abdomen as 

 though about to oviposit. Examination of these sites has so far 

 not revealed any other stage of the insect. 



SYRPHUS KNABI Shannon. 



(Syrphus xanthostomus Willist. of Metcalf in Ohio Nat., Vol. 

 XIII, No. 5, pp. 81-83.) 



In the Ohio Naturalist for March, 1913, I published a de- 

 scription of what was called the Pemphigus-Gall Syrphus-Fly, 

 under the name of Syrphus xanthostomus Williston. 



I was aware at the time that Williston's rather brief descrip- 

 tion did not fully cover the adults under observation, particularly 

 in regard to the distinctly yellowish lateral margins of the thorax 

 and the absence of the median, narrow, deep, emargination in the 

 posterior margin of the second and third yellow abdominal bands. 

 However as Williston's type was not examined, certain points of 

 discrepancy were simply incorporated in the description of the 

 adult and no new name created for the species discussed. 



