Second time posting after hitting the wrong stinking button! :angry:
What Peter said is spot-on. I have conducted my own experimentation with Shields and found that the mortality rate was significantly lower when they were separated out into individual cups very early after hatching, but while you *could* theorhetically raise all 200+ nymphs to adulthood with the proper care & housing, would you really want to? Who has the space or sheer willpower to care for so many mantids at one time? :blink:
The reasons I raise prices as the nymphs get older are: 1) many nymphs are lost in the first couple of molts, so if I am losing one to a mismolt or cannibalism for every one that remains, I have to charge more for the survivors to make up the loss, 2) my time spent caring for them, and 3) older nymphs are hardier & more stable for the buyer.
The reason adults are so expensive is because they have survived all the way to adulthood! The final molt is the trickiest for most species, with the first & final molts being the ones with the highest mortality rates. If you want a perfect breedable adult, with no wrinkled wings or bent legs, you have to expect to pay the price.
That being said, remember the old addage, "You get what you pay for!"
If you have the knowledge & experience, then maybe buying $2 nymphs is a pretty good deal, but if you're new & inexperienced, it could just be a waste of money (when you should've spent a little extra money & bought something older & hardier.)