Window screens are uncommon in New Zealand.

It’s not that there is no need for them. This time of year I struggle to keep the outside out of the house.

Flies, bees, wasps, mosquitoes, and moths all find their way in, to buzz, bite, and generally be a nuisance. Leaves and seeds blow in on the ever-present wind. And the occasional escaped chicken or feral cat wanders in, too.

So why no screens?

It makes sense if we look at why window screens are found elsewhere in the world.

In the United States, window screens were uncommon until the early 1900s, when they were suddenly mandated by local governments all over the country. An important advance of science was the reason for the new laws.

Today, with think of malaria, yellow fever, dengue, and a host of mosquito-borne diseases as tropical. But these “tropical” diseases, especially malaria, used to range all through Europe and North America. The ancient Romans invading Scotland, lost half their soldiers to Scotland’s local strain of malaria. Yellow fever and malaria were common in Boston and London. Philadelphia was decimated in 1793 by a yellow fever epidemic.

The connection between mosquitoes and malaria was discovered by entomologist Ronald Ross in 1897, and by 1900, mosquito control efforts were underway all over the world. Within a few years, window screens were being mandated by law in disease-hit areas. Most of those laws are still in place, as there is nothing preventing those mosquito-borne diseases from returning.

Here in New Zealand, we are remarkably free of mosquito borne diseases. Malaria, and yellow fever have never gained a foothold, though they almost certainly have shown up now and again in the form of sick travellers.

With no mosquito borne disease, the biters that slip in through my windows every night are just a nuisance, so screens haven’t been written into the building code.

But they would be nice to have…