Sun Fly

Helophilus pendulus

Date First Recorded in the Garden: 08/07/2021

Family Syrphidae: Hoverflies

A very familiar family of flies, often mistaken for bees or wasps which many species mimic, but they are totally harmless. Very attractive insects of which there are over 280 species recorded in the British Isles.

This is a family within the order Diptera or True Flies, and have only one pair of wings, unlike most other insects have two pairs (think of butterflies and bees). In most species sex can be determined simply by looking at the hoverflies eyes. If the eyes meet at the top of the head then its a male, if separated its a female. Of course there are some exceptions to this rule as in some species males eyes do not meet. However if the eyes do meet you can be sure it is a male.

Sun Fly – Helophilus pendulus

The genus Helophilus contains 5 species recorded in Britain and along with a few other species are the only species to have the amazing striped thorax. Helophilus is perhaps the most common and widespread of this genus. We certainly see them reasonably often.

Unlike most genus, the Helophilus are one those groups where both the male and females have eyes separated at the top of the head. They are also one of the species who’s larva are aquatic and referred often as Rat-tailed Maggots. Google this and its easy to see why. The ‘Rat-tail’ is in fact the larva’s breathing tube.

In the Garden

We have seen rat tailed maggots in the small pots of standing water we occasionally leave out over the summer months. The chances are some of these will contain at some point the larva of this frequent species.

Indeed we would recommend if you have a large water proof container, such as a bucket, then fill this two thirds with leaves, twigs and clippings and then fill the whole thing up with rain water and stand it in dappled shade through the spring summer. This will act as a safe drinking vessel for inverts (they can perch of the rotting but floating vegetation) and also a place for aquatic larva to develop.

Like so many flies, these guys love the oxeye daisies as is shown in the recording below taken on the 21st August 2023.