Every time I mow the lawn, I feel like a mass murderer. Because we don't do the poison thing to create a greensward as perfect as a golf course, our lawn is chock-full of plants other than grass, many of which bloom -- and many of which I recognize as traditional edible and medicinal wildflowers. All of which feed bees, butterflies, and bugs, if not ourselves, and give shelter to snakes and toads.
For reasons I don't understand, most of those critters don't hear or feel the racket of the approaching mower and fail to get out of the way before it ravages through. I avoid anything I see but am often too late. It breaks my heart and pounds my environmental conscience every time.
You'd think that if I had an environmental conscience I either wouldn't mow at all or would use something besides fossil-fuel-consuming, air-polluting power mowers (one lawn tractor, one walk-behind). But country living has its own rules, and we live in a continual thrust and parry with nature that nobody wins. At best, we maintain an armed truce.
"Lawn" at our place means 2+ acres of open or oddly configured space surrounding a large house with four entrances and three driveways that must be kept open; two outbuildings, three gardens, massive woodpiles, parts vehicles, and materials storage that all must remain accessible by foot or vehicle. It's not the sort of space you putter through with a hand pushmower. (Believe me, I tried!)
Sure, we could wade around up to our armpits in growth and become tick magnets and be pestered intolerably by mosquitoes and biting flies. The moat of lawn keeps them to manageable levels in our living area, and also constrains predators: the cats can't ambush the birds from cover, and neither can the the foxes, coyotes, and fishers ambush the cats.
Then there's the neighborhood factor. Though nowhere near as bad here as in suburban areas, social or zoning pressure escalates when you leave the visible portion of your homestead in scruffy shape. This may change over time but remains an issue, because ungroomed yards make one's place look unoccupied or impoverished or just low-class. Most of us don't want to give that impression to the world.
We compromise by leaving lots of edges, and beyond the utility part of the property let everything run wild. This location backs up to other large parcels so a wildlife corridor remains, including diverse habitat for mammals, birds, and insects. So we feel free to maintain our piece of habitat within it.
When the day comes that disposable income allows replacing the mowers with more energy-efficient or alternative models, using "green" lubricants, and the like, we'll switch to less environmentally harsh tools. Until then, we mow high, not often enough, and cut interesting swaths around stands of wildflowers as they spring up -- and hit the brakes when we see small critters in the grass.