Japanese beetles are terrible but not the only pest of
Last year I duked it out with Japanese beetles from June
until fall. They will eat my rose buds from the inside out, and
they literally covered my bushes before I could even cut buds to
bring them inside to save them!
So I tried a "beetle bag" and even though I followed
instructions (place bag down-wind, etc.) I still had problems. Not
to mention that I was catching probably hundreds every day in those
I cannot understand why I have such a problem. Others
who live 30 to 60 minutes away have no trouble with these pests.
Any ideas? I hate to go through it again this summer.
Japanese beetles are obnoxious, but you may be laying too much
at their feet. For instance, it was probably rose slug that
harassed your roses in June, eating buds from the inside. Japanese
beetles don't operate that way and they favor soft, ripe tissues --
flower petals and leaves -- over green, crunchy unopened buds.
They don't eat all summer, either, but start in late June or
early July, peaking in August. Perhaps you've locked in one image
of last summer and superimposed it on the whole growing season.
That's often done with flowers. People say "it bloomed all summer!"
of a favorite plant, even though an impartial observer will tell
you that cleome, dahlia, cosmos, salvia or threadleaf coreopsis did
not begin to flower until July.
What works against Japanese beetle is not a trick but a tactic
that can beat any pest -- anticipate its arrival. Stop it before it
In this respect, Japanese beetles are easy targets. They all
emerge over short period each summer and that time is predictable.
When snowball hydrangea flowers are turning from green to white,
look for these beetles to dig up from under the sod that's been
nurturing them as grubs since last summer.
Look for them on their favorite plants. Here, too, they are easy
to predict since they favor the same roses, raspberries, linden
trees, Harry Lauder's walking sticks, hollyhocks, etc. each year.
Hunt them early in the day when they are moving slowly. Knock them
into a bucket of soapy water, spray them with an insecticide, or
pick and crush them. At the start of beetle season you might cover
the plants they like best with floating row cover -- that
lightweight cloth sold for frost protection. The beetles are still
drawn to the plant's smell but become stark targets against the
In the case of Japanese beetles early action is even more
important than with other insects since content, well fed Japanese
beetles emit pheromones -- chemical attractants -- that can draw
others of their kind from half mile away. The more beetles that
land and feed in your yard, the more others they "call in." Stop
the first wave and many other beetles will go elsewhere.
Your beetle bags are probably traps baited with pheromone. Throw
them away! The best use for scent-traps, which are custom-made for
each type of insect, is to detect when an insect appears each year.
Given that information, other methods of pest management can be
timed for most impact. Once target insects appear in the trap, the
trap is put away. To leave it out is to invite more trouble.
Marketers, not pest management experts, promote "beetle bags."
Horticulturists joke about finding a fall guy to put up a beetle
bag, at least a quarter mile away, so all the beetles will go
Why do you have trouble with this pest while other people don't?
"Other people" beg to differ. Like all insects, it
proliferates in some localities. Large areas of turf can support
lots of the grubs so people near athletic fields and golf courses
may see more Japanese beetle damage than those near forested parks.
Sometimes wind pushes more insects to the east than the west as
they emerge and begin to fly, or the smell of favorite foods lures
them one way rather than another.
No time to pluck every weed from the
Remove weeds closest to the bases of desirable plants. Then put
a few inches of mulch on the spaces between plants, right on top of
the weeds. Or spread a sheet of newspaper plus an inch of mulch.
Seedling weeds will die and larger survivors will be easy to pluck
later from the loose, moist soil beneath a mulch.
Green thumbs up
to garden center employees whose most demanding season seemed to
have no end this year as rain and cold extended our shopping and
planting. All my best to those who keep smiling and serving, even
when so steeped in the season that they inadvertently address a
greeting card to "Rudbeckia" rather than the intended
Green thumbs down
to giving up on the growing season if you didn't get your garden
planted on schedule by Memorial Day. We still should have at least
70 frost-free growing days, and perhaps as many as 100. That's
plenty of time to see tomatoes bear fruit or begonias fill in, even
if they were first planted in late June!
Originally published 6/21/03