Joe,

I've endured the beetles for over 3 decades. My approach
is peaceful co-existence. The grape leaves look ugly with all
of the holes in them, but my crops have always been excellent
in spite of the damage to the leaves. In my warped opinion, every
hole in a leaf just creates an opportunity for the leaf below to
get more sunlight.

Very seriously, I don't see any real harm to the plants. Currently,
the pesky little bugs are eating my grape leaves for energy,
humping one another, and then dining on grape leaves again.
Sort of like the insect variety of college students.

I still get a great crop and my bigger concern is the bees,
wasps, other insects and birds who will be dining on my crop
when it matures. That is much more serious. Nets help with
the birds, but it is very difficult to keep the insect away.

After the vigorous breeding on my grapes vines, the beetles
will move on to deposit their eggs on my lawn and the lawns of
my neighbors. The subsequent grubs are a non-trivial problem,
but I've even learned to live with that. Of course, that means
that there will be a fresh crop of beetles down the road to
repeat the cycle.

You are extremely lucky if you've grown grapes for 35 years
and you are just encountering Japanese beetles. Others may
disagree with me, but I seriously suggest that you just see
how you crop turns out in spite of the holes in the grape
leaves.

FYI: every year my grape leaves look as if somebody blasted
them repeatedly with a 12 gauge shotgun. Ugly, but still
very productive.

Treating your lawn for grubs may mitigate future problems,
but not very much unless all of your neighbors do the same.
Grubs in any nearby lawns will probably produce beetles who
will feast on your grape leaves next year.

Good luck,
Gideon

PS: Don't forget to harvest some of those tender young grape
leaves early next season before they turn tough and before
they get eaten by bugs. There are many great uses for tender
young grape leaves. I share mine with several neighbors,
most of whom reciprocate by sharing the delicacies that they
make from the leaves.

==============

JoeSpareBedroom wrote in message ...
I guess I've been lucky during 35 years of gardening - this is the first
time I've had to deal with Japanese beetles. They're decimating my grape
vine leaves. I doused them last night with disgusting, fermented
garlic/onion spray that I made last year, which chased them away. Are they a
short-visit pest, or do they tend to move in with their furniture and
extended families once they've found a snack they like?