I am experiencing a problem I have in past years in my garden. Vegetable seedlings suddenly go limp and when I check them I find that, although they are sticking up out of the ground, the root system is gone. Or they simply wilt and fall over and I discover the same problem.

I know it is not a rodent but I do find what appear to be various beetle grubs and caterpillar like larvae of moths???? when I work the soil.

Any suggestions for a potential culprit and organic control(s) are much appreciated. Thank you.