Well, I know more about the lamps than I do about the bugs and their behaviour. What I know is that there was no real standard that was universally adopted for what kind of bulb technology to use in most cities. Lately, almost every municipality has switched to installing LED lamps. Not all pre-LED lamps used LPS bulbs. Some were florescent, some were even HPS or even incandescent, if you go back far enough. From what I’ve been able to determine, sodium vapor was one of the most common at the end of the 20th century. Either LPS or HPS I would assume.
I get the impression HPS was more common, but again, it’s going to vary wildly depending on municipality. HPS has a more spread spectrum than LPS, with plenty of emissions into the far red.
My assumption is that the yellow/red attracts insects because it resembles the sun. Effectively, if a bug is in a dark place (such as a cave or similar internal space, it will aim for the brightest source of light to try to find it’s way outside (where food and other bugs are to mate with). I’m not sure what spectra bugs see, so I’m really only guessing as to whether sodium vapor or LED may attract them more or less than the other. I would assume any infrared would be a desirable wavelength for an insect to move towards, since our sun emits a lot of infrared.
Well, I know more about the lamps than I do about the bugs and their behaviour. What I know is that there was no real standard that was universally adopted for what kind of bulb technology to use in most cities. Lately, almost every municipality has switched to installing LED lamps. Not all pre-LED lamps used LPS bulbs. Some were florescent, some were even HPS or even incandescent, if you go back far enough. From what I’ve been able to determine, sodium vapor was one of the most common at the end of the 20th century. Either LPS or HPS I would assume.
I get the impression HPS was more common, but again, it’s going to vary wildly depending on municipality. HPS has a more spread spectrum than LPS, with plenty of emissions into the far red.
My assumption is that the yellow/red attracts insects because it resembles the sun. Effectively, if a bug is in a dark place (such as a cave or similar internal space, it will aim for the brightest source of light to try to find it’s way outside (where food and other bugs are to mate with). I’m not sure what spectra bugs see, so I’m really only guessing as to whether sodium vapor or LED may attract them more or less than the other. I would assume any infrared would be a desirable wavelength for an insect to move towards, since our sun emits a lot of infrared.
In the end, I’m only guessing.