Ask Alys: your gardening questions answered

http://www.theguardian.com/lifeandstyle/2014/may/17/ask-alys-magpies-lawns

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Magpies are pulling up my lawn. I want to get it repaired or have new turf laid ready for me to laze on during hot summer days. What can I do?Magpies, crows, rooks and starlings are fond of lawn-dwelling crane fly larvae, AKA leatherjackets. In some ways the birds are acting as pest control, and also aerating your lawn. However, they are not the most tidy lawn-maintenance team.

So, for the future, you could use the biological control Steinernema feltiae, a parasitic nematode that is watered into the lawn (Nemasys Leatherjacket Killer is the main brand). The soil needs to be warm and moist for this nematode to survive, and it's best done when you know leatherjackets are present, because the nematodes won't survive for long without a host.

The adult crane flies emerge in late summer and lay eggs in the turf from August to October. Last summer was fairly dry, however, so there may not be as many in 2014 as there were last year (the flies need wet summers to thrive). Once you have treated the lawn, give it a vigorous rake and resow any bare patches with grass seed.

• Got a question for Alys? Email askalys@theguardian.com