At up to 25mm long, the Birch Sawfly (Cimbex femoratus)  is Ireland’s largest Sawfly species. The adult is easily recognised by the pale band on its shiny black abdomen. Wings are smoky brown colour with dark brown margins. The antennae are yellow tipped. This individual was observed this week in Co. Clare by an INIS Ecologist.
Interestingly it was noted on the thick stems of some Japanese Knotweed (Fallopia japonica), see the picture below.