Have I got rid of them?

Hello,
I have a spider plant which has a lot of sentimental value to me. Yesterday I realised that there were lots of tiny little whitish insects all over the soil. I think they may have been mealybugs, but I'm not 100 per cent sure. Desperate to to lose the plant, I got rid of the old soil, washed the roots of the plant ( its still fairly young and small) and washed the pot out. When I went to use my bag of MiracleGro, I found that the insects were in there, too! So I discarded this and bought some new potting mix. I have now repotted the spider plant, and sprayed it with some very dilute soap to make sure all the bugs have gone. I also repotted a peace lily which I had recently used the MiracleGro to repot, as a precaution. I've checked my other plants, and they seem fine.
Will this be enough? How do the bugs get there in the first place? And how did they get in my bag of potting mix?
Thanks in advance for your help!

 

Hello Teri
Your anti infestation procedure is text-book ! if they do persist buy a anti bug spray
http://www.bayergarden.co.uk/en/data/Products/p/Provado-Ultimate-Bug-Killer-Ready-to-Use.aspx
No one in the known universe knows how bugs get where they do . How one plant can be absolutely crawling with them and the next one is clear !!
If you think the MG compost was infested , just leave the bag on the drive of that over fussy neighbours down the street

 

that's good to hear! I'll keep checking over the next few days. Thanks for your help!

 

Naughty Harry