Toxorhynchites brevipalpis, a predatory, non-biting mosquito introduced in an attempt to control biting mosquitos. Unfortunately they never really took off and it's fairly rare to see them. But when you do, they're quite a striking sight - they're big (the body is over half an inch long, and the span of the legs is close to an inch), metallic blue, strong fliers, and make a buzz similar to a regular mosquito but audible from at least five feet away. Two of them kept coming back to a particular paperbark tree near the start of the Kaluaa trail (a pretty dry area) for some reason.