Not true.
Hundreds of studies have been done on this subject, with mixed results. Most are inconclusive because there's many different kinds of LED's and there's millions of different kinds of bugs. Some bugs are attracted to light. Some aren't. Some are attracted to heat. Some aren't.
There were some tendencies identified in the studies. Bugs that are attracted to light tend to be more attracted to cooler tones (blue) and UV light. This probably explains the purple lights in bug zappers. Even though there's no UV light in LED, the bugs still like the blue tones.
Bugs that are attracted to heat will still be drawn to the warmth of a lighting fixture. The diodes get warm and the drivers make the whole fixture warm. So, as it gets cooler outside, the bugs will still come to the warmth, regardless of the color of the light.
Good luck,
CD