Of course he will to an extent but you don't realize that at this point it doesn't matter. All Dusek needed was an expert that would put the date at 2/2 and say this is the minimum time she was there. From this Desek has the testimony he needs.
Whether or not it literally applies to the bug evidence, the jury will be instructed that if two "reasonable" explanations are given, the one that favors the defendant must prevail.
They may choose to apply that principle to the whole sum of entomology expertise, although that isn't eactly what the instruction demands.