Millipedes or centipedes in house plants

I have what appears to be millipedes or centipedes in my houseplants. I have bought sprays and insecticides and yet they still persist. Is there a way to get rid of these things without ruining my plants and how did they get in there since I had...

recentely repotted my plants and I know for a fact they weren't there?

 
They probably got in there as eggs in the potting soil when you re-potted the plants. I'd suggest that you contact a garden supply store and see what they recommend to eliminate them.

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Have you tried spraying liquid seven on them? I recommend this...as it kills most insects

I have a question,I have centipedes on my plant.when I was watering it they came out.there is hundreds of them.I am sure they are not millipedes.will they harm humans?

1. Millipedes came to surface when you watered the plant. - This lead me to try something. I took the 12 plant I had, which was infested as well, and put it in the kitchen sink. the pot covered the sink hole at the bottom so I didn't have to use the sink stopper. I began filling the plant with water. It flooded and I was able to skim the critters off the top along with a few twigs from the potting soil. The water I ran was a little warm. Is this going to kill the plant? I'll find out later on. The water was very warm, not burning hot. The critters that didn't make it to the top simply drowned. I found a few critters with shells on as well. I then sprayed the plant with a light mist of alcohol water mixture. Then rinsed the leaves immediately. Did this hurt the plant? I'll find out later. The critters on the surface of the soil remained motionless. I drained the water. Then turned on the sink disposal. They won't be going to other plants. I let the plant drain since it had good drain holes at the bottom. To accelerate drying time you can put the plant in a breeze (fan, breezeway) that doesn't get bombarded with light. Even if you do put it in direct light for a short period, and even if you drown the plant for a short period, they wont' die. Plants are more resilient than bugs. I think my method work as no one is crawling around my plant anymore. Based on other reactions (I got my spray cause it was the first thing I jumped on) The critters were there before you saw them, one more minute of calming down and thinking will make things go just as well with little risk of collateral damage from panic. Change the environment of the bugs for a while and understand plants are very strong as well as beautiful. I topped this thing off with some plant food to refresh the pot and just a hint of potting soil to replace what I took out- 1 handful. Good luck!