What is this?

They wont be around for long, its not unusual to have them this time of the year 

 . . . . but you still have to get rid of them or more will return later.

Thanks guys but still none the wiser

Looks like a fly maggot, is it coming from behind a solid structure?  Use the spray from Mercadona 'Rapid' in the whole and maybe you'll kill them off.

Thanks thats what I thought but it is bigger and thinner than the fly maggots I used to use for fishing so I had though nope not that plus there is no source of rotten meats, fruits or veg where they might lay their eggs. Any dead mamals in the walls I would have thougth we would have smelt. plus wouldn't a gaff have to be pretty manky for have them around? 

I can not find exactly where they are coming from. I took everything out of the cabinets and sealed any small gaps or holes I found with silicon, which also helps keeping the ants🐜 out,  as a number of us are aware, is a whole other headache,  . 

I did find the hole pictured which, let me tell you, led me to having words with my contractor. Wouldn't say he made a hames of the install but its not pretty

He filled it with expanding foam but I still had a few uninvited quests after that.

so still none the wiser 

Did he use his teeth to make that hole?