Shropshire apperars to be witnessing a plague of greenfly, writes Ben Bentley.

Greenfly. We're facing a plague of them this summer.

The Shropshire countryside has company. Billions of tiny green creatures swarming from the skies, gatecrashing barbecues and playing havoc with plants and crops in gardens and fields.

We might be basking in lovely summer weather at the moment but these are also ideal conditions for the rapid proliferation of common greenfly, or aphids.

In fact, the greenfly invasion seems to have been worse than ever over the past couple of weeks.

“I suspect that it is perfect conditions for greenfly,” says John Hughes, wildlife expert for Shropshire Wildlife Trust.

“We’ve had a warm, wet spring going into early summer and things have been growing very well, so everything that lives on plants, like greenfly, is doing very well.”

The enemy of gardeners and farmers alike, these tiny insects can jeopardise a very wide range of plants both in the garden and indoors, as they infest the softest parts of the plant, usually the tips of shoots and the undersides of young leaves, and suck the sap.

This reduces plant vigour, can transmit plant viruses and deforms leaves and stems.

Greenfly also excrete a surplus sugar solution which creates sticky patches on plants and is often colonised by a fungus called sooty mould that turns the foliage black.

Although this does not directly damage plants it can block out light to the leaves and reduce the plant’s ability to photosynthesise.

Greenfly can be hardy little things, surviving or ‘overwintering’ as adults in sheltered spots outside or under glass – or as eggs on host plants.

Then in spring and early summer adult females give birth to live young without mating – the young are all female so populations increase rapidly.

“They exist in phenomenal numbers,” says John Hughes. “And the reason is that females produce live young – greenfly just pop out of the back end.”

Winged greenfly develop when there are predators about or the greenfly are ready to move to different hosts, but lose their wings when they settle on their new host.

They continue to produce more young, including some males.

“It is something that is always here – greenfly are always around,” says John. “It’s when their numbers escalate that they do real damage, but for the most part it’s not that significant.

“If it’s your prize-winning broad beans or your living – as it is for farmers – that is when it can become a bit of a problem.”

Pip Pritchard, chairman of Gatacre Gardens and Allotments Association in Oswestry, says: “They can devastate your plants and vegetables such as your lettuces or runner beans.

“They get on the stems and can cause disease – then your plants have had it.”

Pip says one of the only ways to prevent the pests getting at vegetables and plants in the first place is to cover cover them in insect-proof netting.

“That will keep most most of them out but it’s like everything else, they get everywhere.”

Failing that, Pip swears by a bottle of Fairy Liquid and washing his plants with a bit of soapy water.

Champion horticulturalist Christine Ffoulkes-Jones, based at Hall Farm in Kinnerley, says: “I’ve never known them like they are at the moment. Wherever you go, you are covered.

“They are falling out of the sky.”

She says greenfly can be a pest and need an attentive eye kept on them.

“It does make a bit of a problem and a bit of extra work but we use biological controls – microscopic organisms in a solution – to prey on them,” she adds.

They might be the enemy of the likes of gardeners and farmers but they are friends to a host of wildlife which flourish at the first blush of greenfly.

John Hughes explains: “I cycle quite a lot and you go out and come back smothered in them – and you realise why swallows and swifts fly around with their mouths open, having a free lunch.

“They are a bit of a pest if you are a gardener and if you park your car under a lime tree and it gets covered in this sticky stuff that aphids secrete.

“But for other forms of wildlife it is feeding time. Everything is doing very well on it, and some blue tits are having their second or third brood on such insects; food sources such as greenfly are an important part of that.

“But when you get a big explosion of greenfly, you get this secondary explosion behind it of predators that live off them, like ladybirds, that will take the population back down.

“Nature holds this balance over quite a long period and gradually the numbers of greenfly will diminish.”