Matt Ridley: We need to defeat one particular mosquito before it gets us

Cancelling the Rio Olympics would do little to slow the spread of the zika virus. That horse has already bolted: more than 60 countries and territories already have zika. It will soon be almost anywhere that its mosquito host lives. Now that the link with microcephaly is well established, becoming pregnant in any country with zika carries a small but real risk of birth defects for the baby.

In the 1970s, troubled by the risks of using pesticides, we took our eye off the fight against mosquitoes and the diseases they carry. Zika is just the latest evidence that we are paying a heavy price for that.