Crows are destroying Cambridge University lawns

The immaculate lawns of Cambridge University are being spoiled by crows feasting on bugs after an EU ban on a pesticide, it has emerged.

This population of the pests has soared after the spray containing a chemical called imidacloprid was outlawed because it is toxic harmful to bees.

As a result crows have had a field day digging up the lawns looking for the chafer bugs, a soil-dwelling beetle which feasts on the roots of the grass.

That makes the lawn vulnerable to damage and when the crows dig for the bugs the weakened grass roots mean they also dig up the turf.

The famous lawns at seven colleges are reported to have been affected and two, at Jesus and Pembroke, are having to be re-turfed.

The colleges have introduced nematodes, worms that eat and destroy the chafer grubs, in a bid to combat the problem.

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But that is not without its problems and Jesus College had to re-turf their entire first court lawn because the area is unsuitable for nematodes.

A post on its Facebook page said: "The situation has become quite severe over the last two to three weeks and large areas of lawn have suffered as a result, First Court in particular.

"The use of nematodes has proved unreliable.

“Our gardeners will apply topsoil and seed along with fertiliser, which the birds dislike, once the destructiveness has ceased."

Some people are asking why some colleges are affected and not others.

Paul Gallant, the head gardener of Selwyn College, said it all depends on the type of soil.

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He said: "The grubs like light sandy soil like the soil at Selwyn. Wolfson and Robinson don"t have the problem because they"re on clay."

Thankfully because the chafer beetle cannot fly very far or very high making it hard from them to travel between colleges.

However, Mr Gallant said that Selwyn"s infestation had come over from the Sidgwick site.

In April 2013, the EU enforced a Europewide ban of three bee-harming pesticides called neonicotinoids, including the chemical imidacloprid.

In January 2016, this ban was reviewed, but in April it was confirmed that imidacloprid is highly toxic to bumblebees and was taken of the market.

The winter weather could halt the problem temporarily as the cold will make the grubs go deeper into the soil and out of range of the crows.

But if they do burrow down the problem will come back in spring, just in time for the annual May Ball.