There is a certain balance that exists in nature when it comes to insects and their relationship with trees and most types of plants. The general consensus is that they all enjoy the same kind of symbiotic inter-dependant interaction like the bees do with the flowers they pollinate. While in that case what is happening is truly beneficial to both parties and the insect is living off of the product in the same way that the farmer has to plant as much as he plans to harvest, that is not always the case.
The reason there are so many beneficial kinds of tree treatment for bugs is that there are insects that truly do much more harm to the trees that most people would believe. Keeping with the before mentioned idea that there is a balance to everything in nature, then it would make sense that there would be both insects that have a role in the creation of new fruit and those that only have a part in their destruction.
The biggest problem is that when people come across services like the tree treatment for bugs, they automatically assume that it will also harm the tree and taint the fruit that may end up in the hands of some poor sap. These conclusions come as a result of misinformation or a stubborn refusal to believe that insects can sometimes play a bigger role in the deterioration of trees that even humans can.
I will extend an olive branch and say that many similar methods of pest control in the past have indeed been as bad for the plants as they have for the insects, but things have changed quite a bit in recent years. Most products now are more considerate towards the environmental ramifications that too many chemicals could have not just on the plant they are applied to, but also to the greenery surrounding it. In order to minimize any adverse effects as much as possible, most tree treatment for bugs services will first do a thorough inspection of the tree and then recommend the best available option to take care of the problem.
Again, I will say that if you don’t want to take the risk of spraying a perfectly healthy tree with any kind of spray or substance, that is entirely alright. But a tree infested with insects that are chewing it down to the bark, or that are carrying god knows what kind of diseases, is not by any definition a healthy tree. In such cases, you won’t have to worry about any chemicals, since the insects will cause much more harm than even the more toxic variety of spray.