Possibly but unlikely as red spider mites are tiny hard to see things. You tend to see the web structure they create than themselves.

Are you sure they were "insects" ?

Did they move?

What is in my mind is slow release fertiliser granules!

Did you plant into a pot that had last year's compost in it?

Red ants.....?.if so take care their bite is really painful

Thank you for all your help. Yes I did plant in last years compost Bamboo but removed some of it and put some new in and then put chicken poo in. Yes they were running all through the compost Teegee. I' ve never seen them before.

They do look like red ants Pamg. I shall put some ant dust in the tub.

If you get bitten vinager can helptake the soreness and itching away in the shortterm

I suggest you remove the plants you've just put in there and turn the pot out - sounds like there's an ants' nest in there, so best spread out the compost to break it up and let the ants all clear off elsewhere.

Thank you for your advice.