What are these things that look like gi-normous vine weevil grubs?

I was expecting to see a picture of chafer grubs, but they're creamy white with a brown head and 3 pairs of legs - can't see if this one's got legs, but it could just be a moth larvae if it has no legs, not sure.

I dropped two on the path and they vanished whilst my back was turned. The next six I put in a saucer with a bit of earth and many short legs appeared, tan coloured, and waved around. They are about an inch long when uncurled.

I am wondering whether I can use the soil as I was planning to go half and half with new and old in the tubs this year.....

I wouldn't as there is the possibility of their eating the roots of whatever you plant.

Agree with Moongrower - even if they're moth larvae, they eat the roots of plants, so dump the compost and use all new.

Okay, thanks. Nuisance...... :-(

Better to dump the compost and have living plants than use old, spent compost and have the roots of your plants eaten. Bulba and I don't 'do' tubs with annuals or whatever in them but if we did I would completely change the compost/soil each time, risk of disease and bug build up.

Yes I'm sure you are right Moongrower, it's what I usually do but getting rid of the soil is becoming a problem now so I thought I might try cutting back a bit on the new ......however it is clearly not to be!