An unexpected garden visitor – The Locust Blowfly (Stomorhina lunata)

Stomorhina lunata at Southport 29th July 2020 (Natalie Hunt)

Like many others, I’m spending even more time in my garden than usual with the current Covid situation. Although I’ve been photographing the insects in my Southport garden for over a decade, this extra time has resulted in a greater number than usual of new garden records but none more interesting than a fly I found late afternoon on the 29th July.

Wandering up and down the herbaceous borders, camera in hand, I spotted an insect I didn’t recognise, an attractive stripey fly with very metallic-looking eyes resting on Phlox paniculata. I snapped a few photographs and having exhausted my field guide resources, sent the images to Phil Smith who in turn, passed them onto Phil Brighton.

To my surprise, Phil Brighton reported it to be the locust blowfly Stomorhina lunata, an occasional migrant to Britain and a possible first for VC59 (South Lancashire)!

The locust blowfly, as the name suggests, predates on the eggs of locust species and is typically found in Africa where it is recognised as an important natural control of locust outbreaks. It has also been associated with termite nests.

The earliest records in Britain are thought to date back to around the 1890s, based on additional information provided by Olga Sivell (National Recording Scheme Organiser for Calliphoridae), with most records concentrated in southern England. In recent years, the species has been rapidly spreading across Europe and sightings in Britain occurring more regularly, usually between July and November, including records from the north coast of Scotland (Rhodes and MacDonald, 2018).

According to Greathead (1962), adult locust blowflies have been observed feeding on a wide range of flowering plants including those in the daisy and borage families so it’s thought it could survive for a reasonable length of time in a variety of different habitats. The paper also discusses the possibility of the fly breeding in grasshopper eggs in the absence of locusts which may go some way to explain its range expansion.

I’ll never cease to be amazed by the incredible distances such small insects can travel. I wonder what will turn up next in my garden?!

Stomorhina lunata at Southport 29th July 2020 (Natalie Hunt)