St. Mark's Fly

The Duck says that they are St Mark's Fly which appears around St Mark's Day, 25th April. Should I tell them to go back to bed for a few more days? 

https://www.woodlandtrust.org.uk/trees-w...ark-s-fly/

Hawthorn are flowering here now and your link says that is one that they help pollinate so may be they were told to wake up by the local hedges. There were some about today when we went for a walk.