From my own experience I would say Gold packs are the best because it seems the wasp is a high end rare compared to the others.
From my last 2 gold packs I managed to get 2 wasps in each pack bringing my total amount to 11.
Or you could find a nest of wasps because then you have an unlimited amount.
How do you keep them everytime I get one I use them I try not to use em but it’s hard.
Spawn one in Forge.
I’ve gotten more in silver packs. 6 out of 22 packs.