Helophilus pendulus is a European hoverfly, associated with a wide variety of waterbodies, from large lakes and rivers down to areas as small as ditches, small ponds and muddy puddles. The larvae are aquatic, living in rotting vegetation in muddy conditions at the sides of ditches and ponds, even in puddles.
Like other members of the genus Helophilus it has black and yellow longitudinal stripes on the upper surface of its thorax. The abdomen is patterned with yellow, black and grey. The body length is 13 mm.
This species visits flowers, it also commonly rests on leaves.