Wasps?

I've got rid of wasp nests by using the aerosol type killers from most DIY stores. You can aim the jet into the nest hole from some feet away. Wasp nests underground are usually in an old mouse hole. You do need to indentfy the entrance and get the jet in there. Ideally borrow some clothing and a veil  from a bee keeper. If not wear a woolly hat pulled down as far as possible, a boiler suit or eqiv. tied at ankles and wrists, gloves and high boots and goggles if you have them. Try to do it at last light, when you can still see the hole but when most wasps are inside. keep away from the nest the next day. Take some Piriton if stung. Good luck.

Good grief we've now sprayed it twice to no avail!
The entrance is quite small about 50p sized and it's quite high up on a mound of earth so son number 1 aimed for the entrance and the foam that came out stayed put around it only it's rained the last two night and it's just washed the foam away and the stupid wasps are still thriving. I'm more scared of them now as I think they must know I'm trying to kill them off and will try and get me first! 
I will need to leave it for now as it's still forecast rain for the next couple of nights and the foam is no good unless it stays put.

Had a wasps nest on my plot last year.  Couple of the guys suggested pouring diesel into the nest as they dont like it.  You will all be glad to know that I didn't for fear of contaminating my and my neigbours plots.

I left the nest alone.

Upshot is the the wasps picked of loads of insects, they didn't bother me as I didn't bother them.  Didn't work the area where the nest was last year but have started to dig it over this year with no sign of activity at all.  Advice I was offered is to be careful of them towards the end of the season when they are "drunk" on all the sweet nector of ripe fruit.  They can get very aggy at this time

I nor the children got stung at all last year! (famous last words)

Good luck in your attempts to kill the nest off.

Raisedbed