Predatory insects and spiders can play an important role in reducing the number of damaging crop pests. With a little help, farmers can boost their numbers, reducing the need to use pesticides in the countryside.
We know that over-wintering habitat is often lacking in the modern agricultural landscape, especially in the middle of large fields.
Understandably, it’s a long way to travel when you have short legs, so we can create refuges for them in the form of beetle banks.
These are long, thin strips of perennial grasses which fit in well with agricultural management and really take very little maintenance. Once the spring warmth arrives, predatory insects will be well positioned to travel out into the crop, doing us a big favour as they go about their daily business predating species such as aphids.
1. During normal autumn cultivation activities, create a ridge or earth bank approximately 0.4 metres high and 1.5–2 metres wide by two-directional ploughing. The beetle bank will run to within a sprayer’s width of the field’s boundary hedge. Leaving this gap helps to reduce interrupting agricultural work and also reduces access to the bank by ground predators which may predate ground-nesting birds and small mammals such as harvest mice.
2. Once the ground has been prepared, the ridge should be sown with a mixture of perennial tussock and matt-forming grasses such as cock’s foot, timothy and red fescue at a rate of 30kg/ha. These should be planted either when the ridges are formed or the following spring, which avoids a harsh winter affecting germination.
3. Opportunistic weeds can be dealt with using a broad spectrum herbicide. Once the grasses have been established, they will do a great job of out-competing other weeds.
4. Beetle banks can also be floristically enhanced with flowers, which not only creates a nice nectar source but will also encourage other predatory species such as hover flies and parasitic wasps.
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