I say white grub population control because most folks will reach for the rifle the instant they see 1 or 2. The fact remains that many more grubs should be visible before conducting warfare (9-12/sqft). There are about 8 major types of grubs in NH/VT that cause turf damage ranging from the classic Japanese beetle to a masked chafer.
As always, the best defense is a good offense. Healthy turf can withstand root pruning and even minor damage without a pesticide being applied. Proper cultural practices also help keep your lawn cooler and less desirable to adult beetles like irrigation and a high mowing height. Overseeding with resistant turf varieties can also help the turf taste less desirable, not necessarily for grubs but their buddies above ground like chinch bugs, sod webworm and such.
New and old research shows us that some compost tea/seed inoculation treatments actually help grass develop its own immune response to reduce damage from both insect and disease activity. Beneficial nematodes, although not any easy turf treatment; provides 100% organic control by using these microscopic predatory worms in the spring or fall. Milky spore disease was developed a long time ago to control only Japanese beetle grubs, not the other 7. Unfortunately, the spores take years to spread/develop and the cold New England winters don’t allow for this disease to function well at all.
There are new oil blend pesticides which are also organic or natural in composition which show promising results to white grub population control in a lawn setting. The more traditional pesticides function in a variety of ways and vary in results. Utilizing newer products over older ones are important to help reduce chemical resistance over time. When using any pesticide, whether organic or synthetic- it is always important to read the label and use the product at the recommended rates as good environmental stewards. Using the wrong product for the wrong pest is not only a massive waste of time; it’s a waste of money and most likely will harm beneficial insects.
In summary, there are lots of ways to help your lawn look great, with the best and least environmental impact being the cultural and day-to-day upkeep of the turf. Integrating resistant grasses during lawn overseeding/establishment and implementing organic or natural bacterial and friendly fungi are super tools with no harmful side effects. In my opinion, pesticides should only be used as a last resort or when there may be a history of continual damage in a scale that would outweigh the omission of such products. In other words, a $400 treatment outweighs a $25,000 renovation for sure!
Control measures come back to each of our own expectations and threshold level of acceptable damage. Are you willing to accept a little damage and forego pesticides or are you more inclined to try some organic options? Planning now allows you to look at all available control measures since many have a narrow window of application and good results.