Impact on the Ecosystem
Most species are innocuous, feeding only in their host plants, and are seldom encountered by humans.
Some of the species, because of their feeding behavior, will leave cosmetic scars in fruits. Some cause damage in cotton and other crops. If numbers become too great
, a crop can fail. http://insected.arizona.edu/stinkinfo.htm
In other words, I would leave them alone. Nature has checks and balances for things. Unless you have an enormous amount of them, I would not bother.
If you must get rid of them, the most effective way is to hand pick and destroy squash bugs and eggs. Please get a positive ID on the bug and the eggs before you sdo this. You might otherwise be killing eggs of a more beneficial insect. Another option is to place boards (or some other flat thin material that will not harm the soil) on the ground next to the plants. At night the squash bugs will congregate under the boards and can then be "squashed" each morning.