Readers reply: Which organisms are most beneficial to humans without us realising?

Pollinators such as honey bees are vital to our ecosystem. Photograph: Dominika Zarzycka/SOPA Images/Shutterstock

I was recently beset by a plague of clothes moths. After hours of research, I discovered the miracle that is the parasitic wasp, or Trichogramma evanescens – near-microscopic beasts that you can order online (in sachets of 2,000 wasps!), the life’s calling of which is to destroy clothes moth eggs.

It made me wonder: is there anything else in our daily lives that is so beneficial to us, but which few of us have heard of – or realise is there? John Forward, Brixton