Male or Female?

I wonder why it is that we (or I, at least), seem to refer to insects etc., all as “he”. Yesterday, getting hold of a book at work to fill in some information on, I suddenly spotted some legs moving on the edge of it! With an aggghhh! I quickly dropped the book, and made the person next to me jump!
Yes, you`ve guess it, it was a spider. It dropped to the floor and I said there he is. And it dawned on me later that I tend to always say he, when describing creatures etc., yet, there must be female ones. Wonder why they are all `hes` to me? Do others do the same? But thinking about it, as I write this I realise there`s an exception to that… I call ladybird`s `shes`! Maybe its because of the colour?!