Japanese Beetles?

This is the time of the year for the annual infestation of Japanese beetles (Popillia japonica). We get a distant early warning of their approach from the vineyard owners in the Mid-Atlantic. For the past 2 years, while our vineyard has become repopulated with vines, the numbers of Japanese beetles appears to have declined.

In 2014, the year after we planted our 6800 vines and the year that we saw only 600 vines survive, we had Japanese beetles everywhere. I blogged about it in a post that I called Beetlejuice because I was using soapy water to catch the critters to lead them to their demise.
How does soapy water work to end the life of a Japanese beetle?¹ Beetles breathe in a way that is fairly sophisticated, using up to 18 tiny openings, called spiracles, that dot the middle and hind part of their bodies. When the pores open, oxygen-rich air can diffuse into tracheal tubes hooked up to the holes. The oxygen then gets shuttled through thousands of interconnected and branching tubes and dumped into cells. The waste product, carbon dioxide, then travels through the tubes and out the holes.
When soapy water is used to capture the Japanese beetles, it is effective in sealing the spiracles thereby preventing them from breathing and ultimately leading to their death. I took particular delight in catching and killing Japanese beetles in this way. My husband said this activity was not sustainable.
Knowing the lifecycle of the Japanese beetle can be helpful in their control. I found an excellent Japanese beetle lifecycle representation in the Sacramento Bee.²

Since we don't use any pesticides or herbicides in the vineyard, we feel that we are allowing the natural predators to be our first line of defense against the invading Japanese beetles.
Natural Control Strategies:³
Parasitic wasps like spring tiphia wasp (Tiphia vernalis) and the beetle’s natural enemies like the Istocheta aldrichi fly are another grub control measure. Starlings are the best known beetle-eaters, eating both the grubs and adult beetles. Other birds known to eat grubs are robins, crows, grackles, catbirds, sparrows, bobwhites, blue jays, eastern kingbirds, woodpeckers and purple martins.
If you see birds pecking at your lawn chances are they may be hunting and eating beetle grubs along with other garden and lawn pests. Japanese beetles prefer to lay their eggs in turf grass that is short, avoiding grass that is more than 2 inches high. Tall grasses harbor natural beetle egg predators like ground spiders and ants. They consume large numbers of beetle eggs in the soil even before they hatch, so keeping your grass on the taller side may be a good defense against the onslaught of Japanese beetles.
We are crossing our fingers and hoping that our natural born predators are consuming copious amounts of Japanese beetle grubs and adults!
References:
1. Jeanna Bryner, Beetle Breathing Highly Complex, Study Finds, Live Science, May 17, 2007.
2. DEBBIE ARRINGTON, Threat of voracious Japanese beetles persists, Sacramento Bee, July 16, 2016.
3. Master Gardeners of Hamilton County, TN, Japanese Beetles – Start Preventing Next Year’s Crop Today, June 17, 2010.