The very large appendix (membranous flap on the wing tip) and very short head indicate Idiocerus; the way the crossveins align on the wing tip indicates the species. -- Andy Hamilton
Range
native to, and widespread across Europe, adventive in NA(2), now widespread in ne. US & adjacent Canada (NF-ON)(3)
Season
Jul-Oct in the UK(1); this and other related species of Idiocerus overwinter as adults, becoming sexually mature in spring. -- Andy Hamilton