Adding just a little bit to what Carlton already said
(hi Carlton! Long time, no see!)
Superworms, silkworms, hornworms are a great addition to roaches and crickets. My own personal opinion is that roaches are FANTASTIC!
If you want to try a safe, clean source for houseflies, try Skipio's. It's been at least 5 years since I ordered from Skipios, but they offer housefly pupae at a GREAT price. Looks like they now offer 1 oz for $11.50, 8 oz for $40. That's a LOT of flies!
skipio's

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Victor Gomez
gomezvi@yahoo.com