It has long been assumed that insectivorous bats are good for agriculture, but only recently have their effects been measured directly.
Experiments in the US show that the numbers of corn earworm caterpillars increase by nearly 60 per cent when bats are excluded from corn fields, resulting in 50 per cent more damage to the crop. Not only do bats eat the adult moths, but they also seem to frighten them off.
In addition, the presence of bats suppressed harmful fungi that are transmitted to the crops by herbivorous insects.
Globally, bats could be saving more than $1 billion worth of corn crops alone.
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