Hittade det här från en stor uppfödare i USA:
-"While this popular misconception is very flattering, unfortunately we didn't harness the ability to gentically modify insects in the 1950s (which is too bad, we would be rich!).
There are lots of rumors about giant mealworms, and hopefully this FAQ will put them to rest.
There are two kinds of insects, those who go through a complete metamorphosis and pupate (beetles, flies, butterflies, and waxworms) and those who don't (crickets, grasshoppers, roaches, and all true bugs). The difference is that those who pupate have a rapid decline in growth hormone which forces them to pupate, while those that don't keep a constant level of growth hormone throughout their life time.
We found a way to keep mealworms from having that sharp decline in hormone as it is in insects who don't pupate (crickets and roaches for example), so they won't go through metamorphosis. The energy that they would have spent forming a pupa is now spent into growing longer and thicker. There is no hormone, chemical, or vitamin present in a giant mealworm that isn't present in a regular growing mealworm or in insects that do not metamorphose.
While the thought of being perceived as scientific geniuses was a lot of fun, our giants are just not genetically modified."
Saxat ifrån www.rainbowmealworms.net/frequently-asked-questions/
Tror de omskriver det lite snyggt, så att man skall tro att de inte tillför hormoner eftersom hormonet man tillsätter är "naturligt" förekommande hos insekterna.
Står ganska utförligt på Wikipedia om hormonerna:
en.wikipedia.org/wiki/Juvenile_hormone