A new visitor on oil seed rape

St Marks fly

Wandering through a field of rape the other day I was expecting to see lots of honey bees.  It was a bit windy and chilly but the sun was out.  However I saw not a single bee just a veil of  black flies sliding up and down invisible poles, not unlike Mayflies.  I had never seen these flies before and was curious to find out what they were.

http://www.fongw.org.uk/wp-content/uploads/2012/05/stmarksflyR.jpg

St Mark’s Fly

How to describe them to Google was a challenge as ‘black flies on rape’ didn’t match what I had seen but the search phrase ‘black fly with undercarriage down’ hit the spot.

It is called St Mark’s fly (Bibio marci) because the adults appears on 25th April, which I’m sure I don’t need to tell you is St Mark’s Day.  Its other name is the Hawthorn fly, but that’s a bit vague isn’t it?  When the first hawthorn blossom appears is far too variable and as there is none to be seen at the moment I rest my case.  May flies eat your hearts out.

Incidently it is said that on St Mark’s eve, if you sit in the church porch, you can see the image of all those who will die in the coming year.  I’m afraid you’ll have to wait another year to try.

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