MARCH OF THE RED ARMY

FORGET-ME-NOTS can pop up in unwanted clumps in your garden thanks to their ability to conquer new territory. For this, they have an army of tiny allies. Attached to the outside of their seeds is a fat and sugar-rich structure resembling a cake crumb which is irresistible to ants. Once dragged back to an ants’ nest, the tasty treats are nibbled off and the seeds disposed of by worker ants which cart them up to 200 feet away. It’s not just these little blue flowers that get a helping hand. Wild strawberries and wood violets benefit from this ant distribution service. There’s a huge army pottering about in forests and fields. So far, about 10,000 species of ant have been discovered and the combined weight of all the minuscule creatures in this family of insects has been estimated as equivalent to that of all the people on earth. The most common — and arguably the cruellest — of the forest specimens are the red wood ants (below) which once thrived in southern England and Wales but are becoming locally extinct in places where overgrown foliage in poorly managed woodland blocks out the sun and makes their nests too cool. Red wood ants are our trees’ important, if ruthless, protectors. They prey on the aphids which, attaching themselves to a tree’s bark, stick their mouths down to where its sap flows. From this, the aphids extract the small amounts of protein they are in search of and excrete the rest as a sugary substance known as honeydew. This is irresistible to ants — providing around two-thirds of their calorie intake in a season — and instead of gobbling the aphids, they bite off their wings and keep them alive. Unable to fly away, they are imprisoned on the bark where their jailers effectively farm them for their honeydew. And it’s also good for the trees. For a Lancaster University study has suggested that leaf loss is six times less in birches settled by these ants. The plane trees found so commonly in British streets and parks benefit, too, increasing their girth two to three times faster when protected by ants.