Oxford's Wildlife Conservation Research unit found that organic farms have twice the number of butterflies than pesticide/fertiliser-based farms. Last year the British Trust for Ornithology discovered that birds also preferred organic farms. The only butterflies which did equally well on both types of farm were the Large and Small Whites. They feed on the crops.

The researchers suggested that the main damage on 'chemical farms' was done by spraying the hedgerow bottoms, which kills both the caterpillars and the flower species the butterflies use for nectar.