Drosophila melanogaster (wingless) to start.
Drosophila hydei (flightless) later on, then onward into crickets and roaches.
I am not sure what a "size 1" cricket is, but here is a pretty good sizing chart, even though it is in the archaic measurement system we are still forced to use here in the US:
Ghann's Cricket Farm :: Pinhead Live Crickets
D. melanogaster are the same size as the 1/16th crix, hydei are closer to 1/8th inch.