Trees on farms are often attacked by scarab beetles, leaf beetles, caterpillars and sap sucking insects. Birds feed on these, and other insects, including scale insects, moths and flies. Isolated or scattered trees can be severely damaged by insects because they usually don't support bird populations. Birds play a role in reducing dieback. This is around 100 kilograms of insects per hectare per year.
Birds control pasture pests.
Magpies Magpies take thousands of scarab larvae per hectare and can vary their diet through the year to eat the most common insects. Magpies eat underground larvae which they can hear and pick out of the soil. They commonly also eat ground weevils, caterpillars, spiders, earthworms and ants. In summer, a large percentage of magpies eat Christmas Beetles and grasshoppers. Ibis Ibis consume large numbers of insects from pastures, particularly grasshoppers, larvae, crickets, caterpillars, and also eat mice.