Hey Tami,
I think the response was that, according to some very stretched exegesis, insects don't "breathe" as vertebrates do, hence would not have fallen under the Gen 7:22 "kill 'em all, I'll sort 'em out later" description of the Flud. This also lets off things like earthworms. IIRC, when confronted with the fact that, yes, insects DO breath, the response was something along the lines of "But the Israelites wouldn't have understood that, and since the Bible was written for them..." etc etc. There was also an argument about whether or not fish breathe "air". It got fairly convoluted there for awhile.
It always amazes me the contortions literalists will undertake to "prove" the Bible is true from the very first word.