The argument from incredulity is a classic used by young-earth creationists, and more recently by cdesign proponentsists. Dave Scot at Uncommon Descent begins by posing the question “which came first, the caterpillar or the butterfly” and then goes on to present this as evidence against evolution. The question itself is obviously wrong-headed to begin with – even a religion professor with no degree in biology can see that if he has taken the time to inform himself about evolution! The theory of evolution doesn’t say that there used to be just eggs and caterpillars, and at some point eggs evolved the ability to hatch chickens, and at some point caterpillars evolved the ability to turn into butterflies. The evolution of metamorphosis is a legitimate area of inquiry, and while poorly-informed bloggers are throwing up their hands and trying to divert attention elsewhere, scientists continue to work on these questions, and not without results.
As an organism evolves, the precise details and stages of it embryological development will change over time. This field, of how embryos evolve with the ability to become various fully-developed adult forms is central to evolutionary developmental biology, or “Evo Devo” for short. When it comes to metamorphosis, we do have evidence of intermediary forms in organisms that currently exist – a range from no metamorphosis through partial metamorphosis to complete metamorphosis. It does not take much searching online to find evidence of the fruitful scientific research on this subject. From popular presentations to journal articles. Lynn Riddiford is clearly a key name in this particular field, and it is unclear why Dave Scot was unable to find the article she published in Nature in 1999. But this is typical of various forms of anti-scientific creationism: they do not stay up to date on scientific research, because they are rooting for science to fail and don’t want to draw unnecessary attention to those places where it “fails to fail” contrary to their desires and predictions.
My advice to religious believers is this: Stop trying to fight science’s attempts to explain things, and focus instead on asking whether or not your religious views are compatible with the scientific data. If not, then you need to either change your religious beliefs or discard them. But to pretend that the issue is limited to evolution and does not relate to the whole range of science and human knowledge is dishonest, and to try to drag us back to earlier times of ignorance because you do not have the courage necessary to rethink and reformulate is unhelpful – to say the least.