Padraig, You posted this in the Gallery section, you'll get more responces if you post in the Discussion section. I'd like to know about these little dudes too. I'm in Citrus Heights, we have some little tiny black ones that always end up in the skimmer basket or in the filter. Then we've also had one or two of those bigger beetle kind, I find them rather hard to net. They're like super fast deep divers. My kids said their friends pool has lots of them (our pool is new), and that they bite? Maybe I'll ask my pool guy, if he knows I'll pass it on.
Anna

Thanks Anna ... I just noticed I posted in the wrong section when I logged in to see any replies :-)

Yep they do indeed bite ... I've been bitten once by one of the bigger ones. I purchased a smaller, tighter woven net to scoop them up with ... they tend to settle in the corners of the pool by the surface and they are easier to capture there. Unfortunately you have to squish them or they just crawl back into the pool :-o

Our pool maintenance guy said they would be gone in two weeks and he suggested just scooping them out. But its been months and although they are much less in numbers they are still there.