This is what's normally refereed to as a "corkscrew" and these types of images are often seen. But unfortunately its easily explained by a technical explanation. Great photo though!

You may not have seen any insects but in the faction of the second when the flash went off, the rapid flying insects fly through the digital camera's field of vision.

The cork-screw is caused by the wings of insect moving faster than the camera's digital memory can differentiate. So you're actually getting an image of the object as it rapidly whizzed through the picture while the picture was being pulled into the camera's memory. Its known as "Motion Blurr". As much as I wish I could tell you that its a real unexplained or paranormal object, in this case I'm afraid I can not.

But PLEASE PLEASE don't take that as discouragement, I really look forward to seeing more images. I'll enhance the image and hopefully you can make out more.

I've enhanced the anomaly and here is the result.
This is a classic example of a medium/small winged insect moving rapidly across the camera's field during the picture taking process.

Great picture! Actually its a rare picture and perfect example of the phenomena.
Thank you for uploading it!

Cool picture. For those of you who watch SyFy, specifically Fact or Faked: Paranormal Files, you recognize it. Called a "skyfish" sometimes. The extremists seem to think it's something from an alternate dimension.....I don't buy into that. When cameras are put on nightshot, the camera is really touchy and I agree with crystalcross, an insect shooting across the frame creates this effect. Neat-o pic though!!!