During the closing days of July 2004 we witnessed a considerable immigration of hoverflies in Lowestoft. On Saturday 31st July I walked from Pakefield to Kessingland to identify the hoverflies coming in. They were flying about six inches above a calm sea and when hitting dry land some settled on the beach and others moved on westwards settling on the cliffs. The high tide mark was littered with their abdomens and wings. The plants they visited at Kessingland beach were Eryngium maritimum, Daucus carota ssp carota, Achillea millefolium, Leucanthemum x superbum, and Rubus fruticosus agg.
Of the live Syrphidae on the beach there were several Scaeva pyrastri, identified by their black and white abdomens, but typically the most common were Episyrphus balteatus, a strongly migratory species. Predating on these around the food plants were several Empid flies, probably Empis tessellata and a Brown Hawker dragonfly, Aeshna grandis. Sitting on the sea at Pakefield were ten adult summer Black headed gulls Larus ridibundus and an adult summer Mediterranean gull L. melanocephalus. As the hoverflies passed inches above their heads they were snapping at the insects as they flew to the beach. Sand martins Riparia riparia were seen at Pakefield beach to take them to their nests in the nearby colony.
Finally Common wasps Vespula vulgaris and Large White Pieris brassicae butterflies were also seen arriving from over the sea.
Colin Jacobs
Editor’s note: press reports around the time of the invasion suggest that it was not confined to coastal areas but was widespread across Suffolk. Indeed, if the reports were correct, many hoverflies ended up in domestic vacuum cleaners.
© 2004 Suffolk Naturalists' Society
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