We are told that every surface in the house is covered with bacteria (which is true) and that they pose a serious threat to our health. 

The ads ask us to use antibacterial sprays and wipes to protect ourselves from the danger we face. 

There is not a shred of evidence that the normal bacterial flora that inhabits bench tops and other surfaces pose any threat to us. 

On the contrary, there is growing evidence that overuse of antibacterial products is contributing to increasing allergy problems and even antibiotic resistance.

So what should we make of the chemical warfare campaigns we are encouraged to wage against spiders and other insects that invade our homes and gardens? 

If you believe the ads, we need to throw everything at them because of the threats they pose to our health and safety.

Spiders in our houses are not a threat to our safety or our health. 

The two most common spiders found in our houses are the daddy-long-legs and the Huntsman. Neither have a bite which is harmful to humans and neither are at all aggressive. 

The Huntsman prefers to hide in dark, secluded corners and wait to feel the vibrations of its prey before emerging at speed to take its catch. 

This can be disconcerting when they hide themselves behind the sun visor of your car but it is not a sign of evil intent. 

The daddy-long-legs will weave a tangled web in a quiet space to trap small flies and mosquitoes for its meals.

These two spiders are responsible for capturing many small insects in our houses and avoiding the need to use toxic sprays.

We may also be given the message to engage in chemical warfare against some of the species that inhabit our gardens. 

Take the humble paper wasp, which builds those beautiful nests in all sorts of places, as an example. 

We should certainly remove them when they are in places frequently used by humans but otherwise we should leave them alone. 

They feed on nectar but feed their developing larvae on caterpillars that can be pests for many of our plants. 

As much as possible, we should leave them alone so as not to disturb the ecosystems that develop naturally.