The beauty of wasps

By Rachel Shaw

Lincolnshire Wildlife Trust

The word wasp can instill feelings of fear but bear with me because not all wasps have a sting in their tail. 

The familiar yellow and black striped wasp is just one of a massive group of over 9,000 different species – and that is just in the UK. Most of these wasps are tiny, you’d barely be able to see them without a microscope and most are solitary and don’t sting humans. 

One of these must be a contender for the most stunning insects. The ruby-tailed wasp is only about 1cm long so can be difficult to see but when examined close-up, all it’s glittering splendor is revealed. 

The vivid metallic green and ruby colouration of this tiny wasp doesn't come from pigments but is an example of ‘structural colouration’. 

It's seen in numerous insects, including on the wings of butterflies and metallic beetles, as well as in the iridescent colours of a peacock's tail feathers and comes from the underlying microscopic structure. Ridges and transparent layers direct different wavelengths of light in such a way that some colours cancel out and others are amplified. 

Structural colouration was first observed by English scientists Robert Hooke (who described it in reference to peacock feathers in his 1665 book Micrographia) and Isaac Newton, and its principle – wave interference – was explained by Thomas Young over a century later.

Ruby-tailed wasps are a species of solitary wasp. Solitary wasps don’t live in colonies like the common yellow and black wasps or honey bees; instead, the female typically builds a nest by herself, stocks it with pollen, and lays an egg within each cell she has created. 

The ruby-tailed wasps, however, are a little lazier: the females lay their eggs in the nests of other solitary bees and wasps, especially mason bees. When the eggs hatch, the emerging young eat the larvae of the mason bees. Then they eat the food that had been carefully gathered for the young larvae. This gives the ruby-tailed wasp its other name of 'cuckoo wasp'.

Parasitising other bees' nests is a dangerous business, but the ruby-tailed wasp has a number of defences: its abdomen is concave, allowing it to curl up into a ball; it has a hard body cuticle that protects it from the stings of the host species. 

It’s remarkable to think that all this could be going on in our gardens. Next time you see a shiny insect flying past or landing on a wall, take a closer look to see if it has a ruby-red tail!

Bottom picture: David Curtis