Okay so here it is:
…and the horse you rode in on
I am attempting a multi-layed pun here. We get biting March flies in Australia, I have no idea why they call them March flies, probably because they are prevalent in March? Though I have been bitten by them at other times of the year. In any case they are not the same as March flies in other countries which don’t bite and actually look entirely different. The Australian March fly, from what I can tell is the same as the Horse fly in other parts of the world.
So back to the Senryu, and my oh so clever punning. and the horse you road in on is a shorten form of “Screw you and the horse you rode in on”. Get it horse fly, horse you rode in on…*wipes tears from eyes*.
And then the reference to the month again.
No? Oh well I tried.