Staff at Leicester's Central lending Library had a shock recently when this large yellow mystery insect turned up. As staff ushered it outside, Matthew Barker was on hand to take a photo on his phone. Matthew sent the image to NatureSpot where it was confirmed as Cimbex connatus, a rare sawfly, and believed to be the first record for Leicestershire! More...

This species had not really been seen in Britain for about 50 years before one turned up in Wiltshire in the early 1990s. Over the past decade or so it has spread quite dramatically all across the south of England and up the east coast as far as Yorkshire. A number of the records have been from places where Italian Alder is present as amenity planting and it is temping to speculate that these insects are a continental strain which may have been introduced, although there is no real evidence for this.

The larvae feed on alder and are large (~50mm), green, with a darker stripe running along the length of the body. It might be possible to find them curled up on alder leaves in the area late in summer. The size of the adult is about 3cm in body length - it is a really impressive insect.

Find out more about Cimbex connatus.