I am trying to find which are the best LEDs and voltages to do the phototaxis experiments.

For that, I was doing experiments with big and small white LEDs (the big ones are much more brighter than the other ones), and with two different voltages: 2,6V and 3V.

This are the results that I have obtained:

As we can see in the pictures, the best results are obtained when we use a voltage of 2,6, and for now big LEDs seem to be better than the smaller ones (we find more differences between flies with clipped wings and flies with intact wings).

But the number of experiments I have done are still not enough to make a good comparison between LEDs size and voltage.