Gnats in dubia colony....

So it was never a problem until they weather warmed up but that's have raided my dubia colony, I've resorted to putting them outside for now but why do y'all do to keep this from happening?

Cleaner Crew
http://www.westcoastroaches.com/?article=140

It sounds like either the moisture is too high (spilled water, lack of ventilation) or there is bad fruit/veggies.

Are you sure they aren't phorid flies?