Classification of Insects (How to develop a method?)

I've been trying this Moody's Mega Math Challenge sample problem, but I don't quite know where to begin.
I only have experience in Statistics up to and including p and t hypothesis testings, and am beginning two sample tests.

My first thought was to do something like (x-y)=standdev. (because the bigger the x and the smaller the y the more sure you are that it is a specific species, and vice versa) but it doesn't have any statistical backing.

I've seen ChiSquared plots, and I thought maybe they would help, but I haven't learned that yet.

I also figured I might be able to do something with the difference of means (the standdev. between them), but they aren't normally distributed.

ANY help, at least to show me in the right direction, would be greatly appreciated.

I have Minitab 14, Mathematica 5.0, and Derive 6, but am inexperienced.
Any help at all. Please.

The problem is Sample #2 "Classification of Insects"