Lost iPhone pictures after uploaded to iPhoto
OK, I had a look around and this discussion might help you. Read all the posts for context but the important one is the last post by Old Toad, he is something of an iPhoto expert on the Apple forums. He says this:

I don't use IC for my imports but have one possible idea: While in the Finder use the Go-&gt;Go to Folder menu and enter &quot;/volumes&quot;. See if there is anything in that folder other than alias to the various volumes you work with on a regular basis.
If you know the name of any of the files that are missing download and use Find Any File to search for it. FAF will search areas that Spotlight can't.&quot;