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Hoverflies in France

 

  In France there are around 530 different species of Hoverfly that are known to be present, albeit many are regional or localised and of course, unlikely as it may seem, there may be more yet to be discovered and classified.

 Hoverflies belong to the family Syrphidae, a family within the order Diptera (true flies). They are then divided into subfamilies and tribes but these divisions, although generally still used, are now considered to be artificial and subject to revision.

  Most people will recognise some of the common ones from their gardens even though they may not know what they are. There will also be many people that may never have seen or noticed them, even more so for those that have lived in cities and spent their working life inside buildings. Often known as Flower flies in the USA and some other countries they have come to prominence as being important pollinators.

  In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores and prey on aphids, thrips, and other plant-sucking insects.  Understanding these requirements will help us provide and conserve the conditions in which they can maintain healthy populations.   Some members of the Eristalini tribe are quite common and breed in decaying organic materials such as run-offs from dung heaps (Eristalis) or in ponds and ditches (e.g. Anasimyia). Some others, such as Myathropa and Mallota breed in wet rotting tree stumps and rot holes.   A characteristic feature of this tribe is the larvae known as "rat-tailed maggots" with a rear positioned telescopic breathing tube, allowing the larvae to breathe while living submerged in water or mud.  Although many people are disgusted if they see these it’s important to conserve them and not think they are something horrible. 

Below a few examples of this type of hoverfly that can often resemble bees.

Above: Eristalis tenax

Above: Eristalis arbustorum

Above: Eristalis sepulchralis

Photo above: Rat tailed maggot, the larval form of the above species.

Below: A fascinating hoverfly is Volucella pellucens. The female enters the underground nests of the common wasp, Vespula vulgaris, or the German wasp, Vespula germanica, and lays her eggs. The wasps it seems aren't concerned by this intrusion and when the hoverfly eggs hatch they feed on any insect remains that the wasps don't use for feeding their own larvae  or any dead wasp pupae, thus providing a hygiene service for the wasps. Fully grown larvae leave the nest and pupate in the ground and remain there until the following year before hatching.

Photo above: Volucella pellucens

Below: Sphaerophoria scripta, the long hoverfly, is common throughout France and many other countries. Eggs are laid on plants where the larvae feed on aphids. They have a remarkably short period from egg to egg laying adult in as little as 16 days with up to 9 generations in a year. Overwinter as larvae.

Photo above: Sphaerophoria scripta, the long hoverfly

Below: Another interesting species is Xanthogramma pedissequum.   Larvae have been found underground in nests of the Black garden ant (Lasius niger) and Yellow meadow ant (Lasius flavus), probably to feed on ant-attended root aphids Forda formicaria and Trama species that the ants collect. Effectively a type of complex symbiotic mutualism involving three species.

Photo above: Xanthogramma pedissequum

Below: Milesia crabroniformis is Europes largest hoverfly and frequently mistaken for being a hornet. They fly in late summer and eggs are placed on rotten trees, often those that have fallen and in old stumps and root balls where the larvae take nearly a year to develop.

Photo above: Milesia crabroniformis

Below: The Marmalade Hoverfly - Episyrphus balteatus is probably the commonest hoverfly in France. The larvae feed on aphids and the adults, which can be seen at anytime of the year, are often in groups.

Photo above: Marmalade Hoverfly - Episyrphus balteatus

Below: The Large Bear Hoverfly Criorhina ranunculi is an early flying species from March until June. The larvae develop in rotting wood. They are known for their aggressive nature towards Bumblebees and other hoverflies.

Above: Large Bear Hoverfly Criorhina ranunculi