By Joan Childs, Rye Meads Site Manager
Rye Meads is not just about the birds. There are lots of different species from animals to insects to plants. Recently I've been investigating the hoverflies at the reserve.
There are more than 270 species of hoverflies in the UK and we have 78 of them at Rye Meads!
I’ve been working on hoverflies since the end of 2008 when I first got fascinated by them while sitting in an amazing wildflower meadow in France! Not only has it been interesting to find out what species we have on the reserve, but also it’s a great group to interest visitors. For example, many of them mimic bumblebees (one species even comes in a red-tailed and a white-tailed form to mimic two different species of bumblebee), honey bees (one species has false pollen baskets on its legs), wasps and hornets.
(Picture on right is a white-tailed bumblebee mimic hoverfly Criorhina ranunculi, Forge Valley)
This is a hoverfly hornet mimic - Volucella zonaria, picture taken at Bav RiverValley in Les Ascles Forest
You are probably already familiar with the tiger-striped orange and black marmalade hoverfly, our commonest species and one of the few to have an English name, and the black-with-yellow-spots Syrphus species, common in gardens, but as a group they are incredibly varied. There are all black ones, hairy ones and shiny ones, and some that are only a few millimetres long. A couple of Scottish species are so rare that the RSPB undertakes special habitat management for them. Many groups, like butterflies and dragonflies, have been well studied in the UK, but there is still lots to find out about hoverflies. We still don’t know exactly how many there are – we are still splitting and clumping them!
This picture shows the Marmalade hoverfly Episyrphus balteatus, taken on Arne
A few years ago, a species called Platycheirus scutatus was split into three different, but very similar species. I was lucky enough to find two Platycheirus aurolateralis, one of the recently split species, on the reserve this spring – the first time it had been found in Hertfordshire.
Another species, Cheilosia caerulescens, is quite new to Britain – it has come into the country on house leeks in garden centres. This winter, I went down to my local garden centre and bought six of the sickest looking house leeks I could find hoping they had the pupae of this species in the soil beneath the leaves. When I checked them this May, I was very happy to find a female laying eggs on the lower leaves . . . but did she hatch out of a pupae from the soil or come from elsewhere? Some species are very elusive and difficult to find as adults, but easier to find by looking for the larvae or pupae. The larvae have many different lifestyles – some live in stagnant water and breath through a long ‘straw’ at the surface, other larvae eat aphids and are therefore the gardener’s friend. Others live in rot holes in trees, the stems of plants, fungi, poo, or ant nests. They have incredibly varied lifestyles so there’s not a lot of room to get bored!
On the left here you can see the house leek hoverfly Cheilosia caerulescens