Ruby-tailed wasp

Ruby-tails

There are a number of Ruby-tailed wasp species that look very similar and are difficult to tell apart. They are all are beautifully coloured, red, blue, green and bronze metallic colours. Their abdomens are usually a ruby red colour which gives the wasps their name ‘ruby-tail’. These wasps are solitary meaning they do not live in large social nests.

Chrysis ruddii © Roger Key

Chrysis ignita is the species of the ruby-tailed wasps that can be found across the UK from April through to September The front half of the body (the head and thorax) is a shiny, iridescent green to blue colour and its tail (the abdomen) is the characteristic ruby red.

Being barely 10mm in length, they can be difficult to spot. You can often see them running restlessly over walls and tree trunks, constantly using their downward-curving antennae to pick up the scent of their host insect. As a parasite they require another species for part of their life cycle, Chrysis ignita mainly parasitizes mason bees and other solitary bees.

Parasite on bees

Once a female ruby-tailed wasp finds the nest of its host insect, it explores the entrance to make sure no one is home. If it should encounter an angry resident, it is well equipped to defend itself; it has a very hard body cuticle which protects it from stings and the underside of the abdomen is concave so the wasp can curl up into a ball.

Ruby-tailed wasp curled into a ball for defense © Laurie Knight www.laurieknight.net

Laying eggs in a solitary bee nest

The wasp reverses into the hosts nest hole and lays its eggs next to the host eggs. The wasp eggs hatch into larvae, which eat the newborn host species. The unsuspecting adult host returns to seal its nest hole, never knowing that Chrysis ignita is inside! This is why this wasp is also known as a cuckoo wasp. The larva complete their development inside the nest and the adults immerge the following spring.

Some Ruby-tails are rare

Chrysis ignita is one of a number of very similar Ruby-tailed Wasp species which are extremely hard to tell apart; Chrysura hirsuta and Chrysis fulgida are classified as Priority Species in the UK Biodiversity Action Plan.

Ruby tail wasp (Chrysis viridula) © Roger Key

Last year Buglife found on of the rare Ruby-tailed wasps at an ex-industrial (brownfield) site in Scunthorpe to read this story click on the link.