How to tackle daddy-long-legs larvae
Organic gardener Sally Smith answers your questions about how to tackle leather jackets. If you have a similar problem,Ìýshare your experiences in the comment section below.
David Kingsland from Ireland asks: I have leather jackets in my polytunnel. How do I get rid of them?
Answer: Leatherjackets are the larvae of the crane fly or daddy-long-legs. Eggs are laid in late summer and the larvae feed on plant roots in the soil. Apart from grass lawns which I assume you aren't growing in the polytunnel, leatherjackets are often a problem for brassicas and lettuce especially on newly cultivated ground. They are most damaging in the spring and summer before emerging as adults in late summer and autumn. Once definitely identified as leather jackets, there is a specific biological control, Steinernema feltiae a parasitic nematode, that is effective in tackling this pest.
It is watered on to the soil and is most effective two weeks after you find the first adults between August and October. Female crane flies lay up to 300 eggs each and the larvae hatch after two weeks and start feeding on roots.
Alternatively, once you have cleared your crops, try thoroughly soaking the soil and then covering with a layer of grass clippings and then sacking or cardboard for a couple of days. The leatherjackets will come to the surface and can be picked off, repeat the process again after a couple of weeks and then fork over the soil to expose any remaining larvae.
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