I once bought a thousand b. lateralis and soon after they were too large to feed to my geckos. It took several months to produce the next generation and grow them to feeder size. When I got dubias, I went with an instant colony so I didn't run into the same problem. If you get a thousand similar sized dubia, you may a have a several month lag between feeder sized nymph and the first generation. So if you want a huge colony someday, get the thousand nymphs. Otherwise get the instant colony.