The petshop has informed me that if the super worms aren't killed in the normal routine of being eaten, they can eat your frog from the inside and kill it. Is this true?

Crickets my local pet store has are brown ones. I personaly havn't seen these to be native to where i live. I generaly see the black ones, are these safe for him to eat? Should i be concerned living in a big city to not catch bugs outside, they spray for mesquito's and who in the heck knows what else people spray etc. I'm concerned about catching my own and having some sort of chemical reaction happen to my frog. Is this an issue i should concern myself with?


p.s I read in another post about cricket shortages. There isn't a shortage here in houston that i'm aware of.