A friend provided me with a link to an article that provides support for the observation that predator insects do help with pest control. Go here.
An interesting side light to this. ISU has study results showing that the aerial spraying for aphids are not providing a statistically significant benefit in yields vs no aerial spray.
Here is some information and here is more.
What interests me about this the most is that anyone who has studied aphids even a LITTLE knows that they tend to favor the undersides of leaves and/or can often be found in the understory of plants they feed on. Further, anyone who works with soybeans know how strong the canopy can become at the stage aerial spraying is applied. Then, add a little physics/natural science knowledge and a little about the technology used for aerial spraying to put it all together and infer that aerial spraying can't get to the majority of the target population of aphids.
I ALSO know that I know just enough to be dangerous here and could very well be missing several things. All I am saying is that just a little bit of thinking makes me question the economic feasibility of aerial spraying for aphids by my neighbors. It just so happens that their spraying annoys me for other reasons - which motivates me to take this to the conclusions I make...and that's why I always hedge a bit. My bias encourages me to ignore facts that don't fit.
So, why do the farmers still spray? Because they are told to do so by those selling the product. And those people tend to use the scare tactic of lost yields in ways that might make pharmaceutical companies look tame....
I know we are not the only rural residents who are becoming more irritated by crop dusting. I want it to quit. It is a danger to our organic vegetable operation. It is a threat to our health with the drifting chemicals. But, before I make too much noise, I need to understand why it seems so important to conventional farmers to make these aerial applications. It wasn't this way until the last couple of years. In fact, crop dusting was a bit more of an exception rather than the rule.
Now, most of August sounds like there are dogfights going on over our heads all day every day of the week. I wish I could find a way for these people to earn a decent living, enjoy what they are doing - and do all that without driving up my own blood pressure!