Hoverflies are a fascinating group of insects. As they are often brightly coloured and very common in gardens many people will be familiar with them. Many have black and yellow markings and so are often confused with bees and wasps. This mimicry reduces their chance of being eaten by predators. However hoverflies are totally harmless and are definitely a gardener’s friend, as the larvae of several common species have a voracious appetite for aphids!
They are also a keystone pollinator group. Due to the variety of life styles in the Hoverfly group we are going to focus on the “Marmalade Hoverfly” for the game.
In the UK, there are around 60 species of dung beetle. By going about their daily business, dung beetles provide an array of ecosystem services and it has been estimated that they save the UK cattle industry £367 million per annum.
Dung is an important source of nutrients. For these to be unlocked and available for plant growth, dung must be incorporated into the soil2. Fungi, bacteria and weathering play a part in dung decomposition but a suite of invertebrates including flies, worms and beetles play a major role. Dung beetles are one of the key players and are often grouped according to their breeding behaviour. The rollers (telecoprids) are typically what people think of – a beetle pushing a neat ball across the African savannah. These do not occur in the UK but the two other groups do. Dwellers (endocoprids) eat, live and breed directly in the dung or just under the soil surface and form the majority of British species. The tunnelers (paracoprids), dig a burrow under the pile and drag the dung down to a metre or more to provision a breeding chamber, where the larvae develop.
By burying dung, the beetles improve soil condition through nutrient recycling and the redistribution of associated fungi and bacteria. As the beetles dig, the soil is turned over, aerating it, and this in turn helps rainfall to enter.
The Common, or ‘Green drake’, mayfly is one of 51 species of mayfly in the UK, and is on the wing from April until September (nymphs are present all year-round). Mayflies are common around freshwater wetlands, from fast-flowing rivers to still lakes, where the larvae spend their lives underwater, feeding on algae and plants. In the summer, the adults hatch out – sometimes simultaneously and in their hundreds; they have very short lives (just hours in some cases), during which they display and breed. Many species do not feed as adults as their sole purpose is to reproduce, dying once they have mated. The name ‘mayfly’ is misleading as many mayflies can be seen all year-round, although one species does emerge in sync with the blooming of Hawthorn (or ‘Mayflower’).
They form an essential feedstock for fish in our rivers and their abundance is a good indicator of water quality.