A great way to boost biodiversity in your outside space is to create as many different habitats as possible. You may have flowers, maybe a pond, a lovely compost heap, even log piles but do you have a hoverfly lagoon??
Hoverflies are often overlooked as a pollinator. They are often mistaken for bees or wasps because of their yellow-and-black patterns which they use as a method of defense although they cannot sting and do not live in nests. The easiest way to know if you are looking at a hoverfly rather than a bee or wasp is to look at their wings, they only have two while bees and wasps have four.
Tiger hoverfly (heliophilus pendulus)
There are more than 280 hoverfly species in the UK and some of these species have an aquatic lifestage with their larvae living in pools of water or ‘rot holes’ in trees. (particularly the genera Eristalis, Myathropa and Helophilus).
This is where the lagoon comes in.
How to make a hoverfly lagoon:
The lagoon is essentially any container with decaying organic matter and water in it. Preferably holding no less than 2 pints of water and positioned in partial shade, ideally under a bush or tree. Once you have situated it, place a layer of dry leaf litter on top of the water, this provides the visiting female with a space to crawl over and lay eggs, it also helps reduce evaporation and deter mosquitoes.
We made ours in an old bath! It worked really well. There are now loads of Tiger Hoverflies using the swampy water to breed. As well as frogs and toads enjoying a cool down.
Check the water for larvae after a few weeks. To spot the hoverfly larvae look for the unique breathing tube which reaches up to the surface, this earnt them the nick name of Rat’s tail maggots. You could keep some in a separate container and like butterflies watch them emerge into a beautiful adult. Or you could take it further and be part of a Citizen Science project which is trying to gather data on our hoverflies see: https://www.thebuzzclub.uk/hoverfly-lagoons