jkn wrote:
Hi Phil

[...]
Just dig around it and replace[1] it with a new hopper, they cost
about £20, then backfill and relay the concrete / slabs /
whatever.....3 hours work at most, and this includes the journey to
pick up the stuff.

Thanks for the suggestion ... it may come to that, but i'm looking for
a temporary fix to do tomorrow, prior to the sort of thing you
outline, to do in a few weeks time.

I'm now thinking of some sort of caulk... recommendations?

Ta
J

Whichever way you choose to fix it, I can't see drain flies having much
interest in this - it's a surface water drain? - that is to say, it's not
soil (****) and this is what drain flies need to survive and breed