if anything, I would think it'd be the opposite. LEDs are pretty capable of more narrow bandwidths natively, but old streetlights used to be a more pure kind of yellowy color, because they were low pressure sodium vapor lamps. Those kinds of lamps give off an incredibly narrow bandwidth of yellow light, and are pretty energy efficient. I would think, as we've made the transition from that to more wide-bandwidth LEDs, more insects would be attracted to the lights, and more insects would die. But I'm not quite sure one way or the other.