Help me fast!

I have my seedlings growing out of a cup and i noticed that one of them was wilting so i further investigated only to find a larva type thing had eaten the roots... they kind of look like a see through worm what can i use to kill the bugs before they kill my other plants

keep them away transplant into something cleaner.

what would u suggest? im using an organic potting soil that is suppst to be steril

please someone help idwt loose my babies!