How to Grow Giant Mealworms

I get asked every week how we make Giant Mealworms.  Well, I decided to stop answering that question via email because I am going to share it right here for everyone to read.

Giant mealworms are treated with a growth regulator.  I have become tired of seeing mealworm sellers state that they don't use chemicals on their mealworms to get them to become giants. Of course, they do use chemicals.  There isn't any other way to do it.

We use a brand called Diacon II to spray on the beds of our giants.  We never use the same bins for other mealworms and the giants are in a separate building so that we do not contaminate our breeding and pet supply stock.


  1.  They cannot breed once treated because the treatment stops the mealworm from becoming a beetle.  It interrupts the process and makes them grow larger instead.
  2.  The chemical is not toxic to pets or people, but it is still a chemical and I would not ingest it.  I also would not feed them to my pets. I say that right on our site at 
  3. If you want big mealworms for reptiles and pets, then use large mealworms or get medium superworms.  Both of those choices are not treated at Worm Man.
  4.  They do make awesome bait.
  5. In order to purchase the chemical, one must be a certified and licensed pest control operator.  I get recertified every 5 years in order to be able to by growth regulator.

Watch our video for more information.