Horticulture Hotline 06/10/19
By Bill Lamson-Scribner
Japanese Beetles have emerged from the ground and are
munching down on our ornamental plants like there is no tomorrow, leaving
behind lacelike foliage everywhere they dine. The warm weather has also caused
the cockroach to move inside for a little air conditioning (can you blame
them?) and the calls are rolling in about chinch bugs and fleas.
Japanese Beetles come out of the ground here around the
beginning of June (as you probably noticed) as beetles. In parts of the country,
they are the number one damaging insect to ornamentals, and they seem to be
gaining a stronghold in the Lowcountry. As recent as five years ago, I can
remember talking to friends in Charlotte, whose plants were getting devastated by
this ferocious eater, and they would say how lucky we were not to have them
down here in the Lowcountry. Roses and Crepe Myrtles are some of their favorite
plants.
Once the Japanese Beetles come out of the ground, they eat
and mate. A female returns to the ground to deposit between 40 and 60 eggs (you
can see how the populations can grow rapidly). The female beetle must burrow in
the ground to lay eggs and the eggs need moisture to survive. A well-irrigated
landscape is a lot easier for the beetle to dig in than a dry, hard, area. The
adult beetle dies off and the eggs turn into grubs over the summer. By mid to
late August, the grub is full-grown and overwinters in the soil. In late May to
early June, the adult (beetle) emerges again and the life cycle starts over.
The grubs from this beetle damage grass and other plants by
eating the roots. Using a product like Grubz Out or Sevin in late August or
early September (if your grub populations warrant treating) or in April will
help your turf; however, do not fool yourself into thinking all your beetle
problems will be solved. The adult
beetle can fly for miles to chow on your precious ornamentals! Milky Spore is
an organic option that seems to do a good job now that our grub population is
high enough for the spores to have a steady food source.
Using a ground drench systemic insecticide in the early
spring like Dominion will help protect your plants, and you might get lucky and
kill a few grubs while you are drenching! Once the beetles are eating your plants,
use a good contact insecticide to kill them. Cyonara and EcoVia EC (National
Organics Program Compliant) are two of the many products that will help control
these beetles. Since contact insecticides have limited residual activity, plan
to reapply the product according to the label.
Traps for Japanese Beetles are a little controversial. The
attractants they use (one is a virgin female beetle scent) can lure more
beetles to an area than the trap can trap! Many ornamentals on the way to the
trap and near the trap can suffer extensive damage.
Roaches, fleas, mice, and chinch bugs are becoming uninvited
guest in many homes and yards. Are you protected from these unwelcome guests?
