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Striped Hoverfly Helophilus pendulus

In the genus Helophilus there are four similar species in Britain. Two will not appear in an ordinary garden, but two will. They do look similar, but it is easy to tell them apart. You have to study them carefully though. First of all they usually differ in the colouring of the markings on the abdomen. Helophilus pendulus has yellow markings, which have more than one colour. But all colours are warm and often there are even some orange patches. Helophilus trivittatus has uniform markings in just one colour: a slightly greenish, light yellow colour. One might say that Helophilus pendulus has markings in the colours of an orange, while Helophilus trivittatus has the markings in the colours of a lemon. A second characteristic are the two small lines on the last segment of the abdomen. In Helophilus pendulus these lines do not meet, in Helophilus trivittatus they do, or almost do. Next is the line on the face. Both species show a line on the face, mainly between and below the eyes. In Helophilus pendulus this line is black, in Helophilus trivittatus it is yellow. Finally there is a difference in size. Helophilus pendulus is the smaller of the two, reaching a maximum length of 13 millimeters. Helophilus trivittatus is considerably bigger, reaching a length between 14 and 18 millimeters.

The larvae of all Helophilus species are so-called rat-tailed larvae, just as the Drone Fly's. At the end of the body is a long tube. The larvae live in organically poluted water. Such waters contain little to no oxygen. So the larvae stick the tube out of the water and they breath this way. Good tactics of course, for there are almost no predators in low oxygen water.