DURHAM DIPTERA. 1 99 



XXVIII. 300. 



16 (17). Wings very clear; abdomen pale haired. 



1574. Eristalis nemorum, L. 

 Hesleden, i $, 26-8-99; Wearhead, 1 ?, 21-8-01. 



17 (16). Wings with a distinct dark blotch about the middle; 



abdomen black haired ; mid and hind tarsi whitish 

 at the base. 



1576. Eristalis rupium, F. 

 Gibside, 1 ?, Gibbsnees, 1 ?, 4-8-97 ; Hesleden, 1 $, 

 15-8-00, 1 ?, 31-8-98; Wearhead, 6 ?, 16, 22-8-01. 



18 (11). Hind femora of the male pale at the base, and of the 



female at least the basal half pale. 

 1577. Eris talis horticola, Deg. 

 Gibbsnees, 1 $, 4-8-97 ; Hesleden, 1 $, 1 % 29-7-99, 

 1 ?, 31-8-98. 



301. Myiatropa, Rnd. 



Myiatropa florea, L. 



Gibbsnees, 1 ?, 4-8-97 ; Hesleden, 1 $, 16-9-99 1 

 Bishop Auckland, 2 ?, 19-4, 23-5-99. "Killing- 

 worth and Harnham," C. Robson. There is a 

 remarkable difference in the size of the female 

 specimens. The two from Bishop Auckland were 

 caught on the window of a greenhouse in which 

 there were no plants received from abroad. The 

 April specimen measures 14 mm., the May speci- 

 men 16 mm. The Gibbsnees August specimen 

 only measures 9 mm. 



303. Helophilus, Mg. 



1 (10). Abdomen ovate; large or medium species, 10-15 mm. 



2 (7). Antennae dark ; abdomen semi-transparent orange ; 



large species, 12-15 mm. 



3 (4). Face with the middle line yellow to orange red. 



(1579. trivittatus, F.) 



4 (3). Face with the middle line black. 



