What are the Dependant and Independant variable of the following?

Ok, so I have a scence fair, and the topic that I have chosen is Are night insects attracted to lights because of the light or because of the heat? My materials are Porch light, Night insects, water, pot. I'm gong to boil the water so it is hot and then put it on my porch and see if the insects come. If you have a better idea please feel free to suggest.