Identification
Lengthwise-striped thorax, transverse-striped abdomen, broad
pterostigma.
Pterostigma of Helophilus and Parhelophilus (Lejops is similar):
Larva's ventral surface with 3 pairs of projections between the anal opening and the base of the long tail.
Key to species by Bill Dean:
1) Tergites 3 and 4 with thin greyish bands; dark fly with sometimes indistinguishable stripes; rare => bottnicus
At least tergite 3 with some yellow/orange markings => 2
2) Yellow/orange markings reduced to sides and tergite 2 usually with narrow pointed inner margins => 3
Yellow/orange markings on tergite 3 large and markings on tergite 2 not pointed at middle => 4
3) Yellow/orange markings on tergite 2 reaching posterior margin in males and nearly reaching in females => lapponicus
Yellow/orange markings on tergite 2 not reaching posterior margin in males, well removed from posterior margin in females => groenlandicus
4) Facial stripe yellow/orange (very rarely darkened); tergite 4 a complete band => 5
Facial stripe coal black; tergite 4 with markings separated => 6
5) Yellow markings on tergite 2 straight on their posterior margins or receding at side margins; scape and pedicel orange to dusky brown; hind tibia partly black; complete band on tergite 4 => fasciatus
Markings widening toward side margins; scape and pedicel coal black; hind tibia partly black; with a complete band on tergite 4; eyes more widely separated => latifrons
6) Tibia totally orange; hind femur orange/yellow on at least apical third => intentus
Tibia partly black; femur orange/yellow near tip or totally black towards tip =>7
7) Black facial stripe noticeably widening towards mouth edge; flagellum at least partly reddish; markings on tergite 2 are rounded on inner margin, receding at sides far from posterior margin; hind femur usually with some orange/red before tip; hind tibia pale at base with a narrow darker band, then orange/red band at middle => obscurus
Facial stripe noticeably widening or more parallel sided; flagellum black; markings on tergite 2 not receding at sides; hind tibia different from above => 8
8) Black facial stripe noticeably widening towards mouth edge; markings on tergite 2 well removed from posterior margin and rounded on inner margins; hind tibia pale for up to basal third; hind femur black to tip => neoaffinis
Black facial stripe more parallel sided towards mouth edge; markings on tergite 2 reaching posterior side margins in male and almost in female, more angular on inner margin; males with long woolly hairs at tip of abdomen; stripe on female frons slightly dusted on upper three quarters; markings on tergite 4 separated; hind tibia narrowly pale => hybridus
Note: if the facial stripe can`t be seen or a rare darker stripe in a fasciatus or latifrons and difficult, then:- tergite 4 complete band = yellow/orange stripe or markings separated on tergite 4 = black facial stripe. (Excepting bottnicus which is so obviously different.)
Range
Widespread, more speciose in n. Canada; ranges from
(3):
H. fasciatus and latifrons widespread from so. Canada to Mexico
H. bottnicus & neoaffinis in far North
The other spp. boreal & western montane
Food
Larvae feed on submerged plant litter
Remarks
Unlike most species of Syrphidae, eyes of males not
holoptic and not different from the eyes of females. Abdominal details are necessary to tell sex.
See Also
Parhelophilus (typically smaller, narrow pterostigma)
Lejops (also with narrow pterostigma)
