I don't think that is a theory that "breaks down under logic". If a person sees a few JBs in their yard, they may respond by putting up a trap or several traps. Once those traps fill up, any remaining beetles may congregate and feed on the person's plants. That situation would be worse than if the person had done nothing at all because there would be a lot more beetles in their yard.
Here's what the Missouri Botanical Garden has to say
"Research has found that pheromone traps attract many more beetles than they catch and probably do more harm than good to plants in the beetles’ flight path and near the traps. Their use is not recommended."
Here's the link to the article
http://www.mobot.org/gardeninghelp/plantfinder/IPM.asp?code=67
I dont buy it..
who only has "a few" in their yard anyway?
they dont really exist as "a few" in my experience..
you either have a mass planting of them, or virtually none..so "a few" you wouldnt notice.
if you notice "a few"..then you have a lot..
Im a belieiver in the traps..
my wife and I have two set up in the yard this year..
they work REALLY well..
we change the bag once a week..its jammed with bugs..
the "smelly" attractant part works all season..
we keep the traps up mid-July through all of August..
IMO, even if the traps do attract from "far away" they still trap WAY more than they attract..
and using the traps is FAR better than not using them..
if we didnt use the traps at all, we would have massive plant destruction..
maybe we are just in a particularly heavy zone..
but I dont think "light" or "heavy" zones really exist..
the bugs are simply EVERYwhere..
all I know is we have significantly less plant damage when we use the traps..
and much less visable bugs ON the plants..(compared to not using the traps)
and the traps are jammed full..
when we DONT use the traps, we have massive JB damage on all kinds of plants..
and we certaintly never have only "a few"..
so in my experiece, the traps are great, and really cut down on the JB problem..
probably by 90%..
Scot