I generally like caterpillars, most do little harm, but the gooseberry sawfly ones are decimating the gooseberry leaves. As for spiders... I don't mind small ones, especially the garden kind, but the ones that take up residence in plant pots... No thanks. I tipped out one pot yesterday and there was a big, fat black spider in it. They're not so bad, they don't move fast. The other pot had a massive house spider type in it. I managed to move the pot, but didn't empty it. I tipped the contents out this morning, just hoping the spider moved elsewhere overnight, or that a bird got it.