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Lawn Pest

When I lifted our picnic blanket from the lawn there were a load of grey maggots wriggling about on the grass. What are they and will they do any harm?

These are likely to be leatherjackets - the larvae of the crane fly. Because they were underneath your picnic blanket, I'm pretty sure thats what they were. Leatherjackets tend to come above ground when you lay something, like a wet newspaper, over the grass. Yes, in large quantities they will do harm since they eat the roots of grass but most lawns can cope with a few. Signs of a bad infestation will be yellow patches on the lawn and, in extreme cases, the lawn will die off in patches.

You can now get a chemical treatment for leatherjackets but I would go with biological control and that's to buy a product containing nematodes which specifically attack leatherjackets. Simply water it in and the nematodes will kill the larve in around two weeks. Another free form of biological pest control is to encourage birds. Crows in particular will pick out leatherjackets for you. Be careful when you pick up leatherjackets as they sometime bite!

Lawn Drainage

In your article on lawn drainage (read article here) you mentioned waving coil. My builder's merchant has never heard of it.

Your builder's merchant might know it as 'perforated land drainage pipe'. Try asking him for that or print off a copy of the pictures contained in the article and take it to him. He'll recognise it straight away from the pictures.

If you have a question for Gardenzine, you can email us at copy@gardenzine.co.uk

If your question is related to a pest or disease, it isn't always easy to tell from just a description alone so, if you can, send us a photograph. Please resize your photographs to reduce the file size.