Eristalis pertinax

Date First Recorded in the Garden: 19.03.2022

Family Syrphidae: Hoverflies

A very familiar and attractive family of flies belonging to the insect order Diptera (or True Flies). They have a single pair of wings, unlike most insect orders that have two pairs. Many species of hoverflies sport a yellow/black colour combination and are therefore often mistaken for bees or wasps, which many hoverflies attempt to mimic. However, they lack the ability to sting and are totally harmless.

With over 280 species recorded in the British Isles, most gardens will at some point in the year play host to more than one species. Many species are considered beneficial as their larvae feed throughout their development on aphids.

Interestingly, in most hoverfly species sex can be determined simply by looking at the hoverflies eyes. Usually if the eyes meet at the top of the head, then it’s a male; if separated then it’s a female. There area few species where this doesn’t hold true because they have males with eyes that are separated, however if they do meet you can be sure its a male.

Eristalis pertinax

The defining characteristic of this species is the yellow/orange tarsi on the front and middle pairs of legs. Tarsi are the final section of the legs. This is a very widespread species according to the Field Guide (1*) and a regular visitor to the garden.

The larvae are aquatic, living in wet, rotting vegetation and breathe through a tube that looks a little like a tail, giving them the apt name “Rat-tailed Maggots.” We often find them in old buckets containing rainwater among dead leaves.

*1: Ball, S & Morris, R. (2015)Britain’s Hoverflies A field guide. Oxfordshire: Princeton University Press.