I don't know anything about mashing insects up, but just curious - is the DNA/RNA extraction from whole insects an established technique? Why are you having difficulty finding out how to do it? I guess I probably know the answer to this already - I've found myself in this kind of situation where there are things that 'everybody' knows how to do, but you don't happen to have any of them at your uni! You should try e-mailing the author of a recent, relevant paper. I've done this quite a few times in the past and most people are really helpful (I tell myself 'that's what the corresponding author e-mail address is for'). There's no need to feel ashamed about something you don't know if you've made genuine efforts to find out about it.