How can I get more female beatles from superworms?

[Wish_mastera]

I've got the folowing question. Has size of the superworm something elese with the sex of the beatle? Female beatles are larger then males. When I separete medium size superworms, they morph into pupas, then into beatles. But they are almost all small ones. Is this means they are all males? If I separate only the biggest and fattest, will they be female, or cant be said for sure? Is the temperature something else with the sex?

Greetings,
Stanislav