50 DURHAM DIPTERA. 



VI. 72. 



25 (24). Male fore tarsi almost bare ; wings with a dark central 



spot and three grey spots. 



435. Chironomus fiictulus, Mg. 

 Bishop Auckland, 1 £, 17-5-02. 



26 (17). Halteres black. 



438. Chironomus nubectilosus, Mg. 

 Bishop Auckland, 2 £, 3 ? , April-June. 



27 (1) (16). Wings quite clear, without any dark tick on the 



X-vein, or wing-spots. 



28 (34). Male fore tarsi with long hairs. 



29 (30) (31). Thorax shining black, not striped. 



(421. disfiar, Mg.) 



30 (29) (31). Thorax green with greyish stripes. 



(425. psittacihus, Mg.) 

 81 (29) (30). Thorax green with flesh-coloured stripes. 



32 (38). Legs all pale. (410- tetidens, F.) 



33 (32). Legs with the fore tibiae and tarsi black. 



(430. m'gri??iajius, Staeg.) 



34 (28). Fore tarsi bare in the male. 



35 (56). Fore metatarsus not white. 



36 (45). Thorax with red stripes. 



87 (38). Abdomen pale yellow with broad brown bands. 



(412. dors alts, Mg.) 



38 (37). Abdomen green. 



39 (40). Large species, at least 7 mm. (410. tendens, F.) 



40 (39). Smaller species, at most 6 mm. 



41 (42). Fore tibiae about as long as the femora. 



(426. viridis, Mcq.) 



42 (41). Fore tibiae much shorter than the femora. 



43 (44). Size about 4 mm. 



427. Chironomus brevitibialis, Ztt. 

 Bishop Auckland, 2 $, 2 ? , May-June. 



44 (43). Size about 2 mm. (428. viridulus, L.) 



45 (36). Thoracic stripes not red. 



46 (55). Thoracic stripes black. 



