Petco, pet smart, Walmart all have good feeder worms. Just smell em. If they smell like they have scent/flavor added (cheese...sometimes they smell like oil?? Best I can describe it). You will be safe with feeder worms at Petco...or just order online.

The fertilized worms from the lawn are a no-go. Just don't do it. I don't fertilize and use the worms in my lawn. Just as lo h as they don't have fertilizer/pesticide.

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Thanks
DW