What are the appendeges behind a crane fly's wings? I noticed that crane flies have strange appendages behind their wings. The appendages look like a pair of antenna or a pair of vestigial wings. In the following picture I marked these appendages with arrows. ![crane fly]( The specimen in the picture sat on my window this morning. I looked through the genera on Wikipedia, that is, on the images if there were any. All crane fly species seem to have these appendages. While the appendages are clearly visible in most images I couldn't find a description of them. I've never seen anything like them and would like to know: * What's the name of these appendages? * What are they good for? Are they vestigial wings, antenna, or some sort of counter weight to stabilize the flight?

They are the halteres. These structures help the flies to perceive body rotation and maintain balance.