Page 17 - ALG Issue 3 2022

hoverflies
One hoverfly larva can munch through 50 aphids per day
Hoverfly do’s and don’ts
DO grow plants which attract adult hoverflies. The adult hoverfly does not have a tongue whereas bees and wasps do. This means hoverflies cannot feed on complex flowers
like foxgloves, penstemon or lavender as they cannot reach the pollen located deep inside the flower. Instead, the hoverfly likes a flower that is fairly flat and open with a little bit of bulk in the centre so that the pollen and nectar is easy to get to without a tongue and so they can take a rest while they feed. In particular hoverflies are attracted to poached egg plants (limnanthes douglasii, also a useful green manure), umbellifers such as angelica, as well as chervil, echinacea, Michaelmas daisy, single dahlias, dill or fennel, cosmos and marigold. They are also attracted to fruit trees with open flowers such as apple, plum, pear and cherry.
DON’Tbeintoomuchofarushtotidyupordig during winter. Hoverflies over-winter in the soil (as larvae) or seek hideaways and crevices to hibernate (as adults).
DO provide water as, like all insects, the hoverfly needs to drink regularly.
DO get to recognise hoverfly eggs and, within 5-7 days, you will have a new batch of very greedy hoverfly larvae seeking out your aphids and other garden pests. Eggs are white colour and oblong in shape and approx. 1mm long and are laid singly on the underside of leaves close to where aphids and other pests are active.
DO provide insect hotels, bundles of sticks and woodpiles.
DON’T use pesticides, soaps, or sulphur bombs as these will kill hoverflies.
We all know about ‘fake news’ but have you heard about ‘fake stripes’? If you have seen a hoverfly at your allotment, you may have noticed they look like
a wasp or bee at first glance. This is because the hoverfly is a talented mimic, using yellow and black ‘fake stripes’ on its body to look like a wasp or bee. This is called Batesian Mimicry, after H W Bates – a naturalist and global traveller who first described this evolutionary step in 1862. And because bees and wasps also taste unpleasant and have a sting in their tail, birds and other predators tend
to ignore the hoverfly and look for another menu choice.
Unfortunately, ‘fake stripes’ are no longer sufficient to protect the hoverfly from the decline in pollinators we have seen in recent years. Hoverfly numbers are generally decreasing at an alarming rate, along with bees and other important pollinating insects which help to keep the planet alive.
There is some good news though; at the allotment we can help hoverflies by choosing to grow certain plants, reducing pesticide use, and providing resources to help the hoverfly thrive. There isn’t a downside to this because hoverflies don’t sting!
The hoverfly is actually a small fly
which has the ability to hover and
feed from pollen and nectar. This is useful for plotholders too as our crops and flowers get pollinated in this process. Hoverflies also have another trick up their sleeves to help out at
the allotment; young hoverflies (as larvae) feed on aphids, thrips and scale insects. One hoverfly larva can munch through 50 aphids per day. With each hoverfly laying up to 50 eggs, that is a lot of hungry larvae to help you on your plot. Natural predators such as the hoverfly can be encouraged to come
to the allotment if we grow certain plants and take a few simple steps. “You scratch my back and I’ll scratch yours” is a great motto for the friendship between plotholder and hoverfly: keep the hoverfly happy and you will be rewarded.
Allotment and Leisure Gardener 17