pests that damage ornamental plants and flowers
Our candid camera has caught
many insects in action over the years...
While working in residential and commercial
landscapes over the past few decades, we have often encountered many of
the same insect pests damaging the same plants. On this page we share
our photos of these pests along with some brief additional comments on
the damage caused by these plant pests.
Black Vine Weevil adults do the noticeable
notching on Rhododendron leaves, but the real damage is caused by the root
weevil stage which damages the roots. A root drench of insecticide to
control the grub stage is usually applied in late June in the
Pittsburgh, PA area.
wouldn't ordinarily include Carpenter Ants with other plant insect
pests. However, after seeing a "tunneled out" wild cherry tree break off
at the base during a windstorm, it only seemed appropriate. Carpenter
ants weakened the heartwood of the tree enough that it blew down,
hitting a house. Carpenter ants are drawn to wet wood.
Dogwood borer is
the most significant pest of Flowering Dogwood (Cornus florida).
Dogwoods planted in full sun are much more likely to be impacted by
dogwood borer than those planted in partial shade, due to their
increased stress level. Avoid damaging trunks with weedeaters and
lawnmowers. Adults emerge in late May.
While aerating this home
lawn in September we noticed the sod was loose and had several brown
areas. Further examination revealed 'C-shaped' Japanese Beetle grubs.
Grubs eat grass roots causing sod to brown and feel loose when you pull
up on it. The many different types of soil grubs are identified by the
pattern of hairs on their rear ends which are known as 'rasters.'
suddenly appear around the 4th of July and "skeletonize" the leaves on
plants. Purple-leafed plums are one of their favorites. The larval stage
is best known for the damage it causes to lawns by eating the roots off
grass, causing large brown areas of turf, mostly in the fall and spring
(see 'grub' photos above).
Chemical lawn treatments are timed for late-summer into early-fall when
the grub is most vulnerable. Biological control: Milky Spore is
effective against Japanese Beetle grubs.
Speckled leaves on PJM Rhododendrons (photo above),
Azaleas and Andromeda (Pieris) are usually a sure sign of lace bugs. Look at
the undersides of leaves to detect active adults during the summer months.
The adults are 1/8-inch long with clear, lace-patterned wings. The
undersides of leaves will also have brown splotches.
This insect will make the
needles on your pine look like they have snow on
them. It's most commonly seen on Mugho Pines
in landscapes, but also infests Scotch Pines. Control the crawler stage
in late May with horticultural oil or insecticidal soap sprays. Dormant
oil applications in fall or spring are less effective.
These blue rug junipers
(photo above) appeared at first glance to
have 'tip blight' fungus.
Upon closer examination, small chewing
rodents (Voles?) had stripped bark off the branches (photo above) girdling
them enough to cause browning foliage on branch tips. We've seen several cases like this
your Pines carefully in May for these camouflaged invaders.
Look first for the areas where needles have been chewed to stubble...
the caterpillars will be close by. They can be sprayed or
black substance on plant leaves usually indicates the presence of a
sucking insect excreting excess honeydew. Black sooty mold grows on the
honeydew giving the leaves a blackened appearance. This 'sweet' honeydew
on the leaves may attract bees as well as ants. Scale insects (white,
top left, in photo above) have infested this Magnolia tree.
examination of the tree branches reveals a large infestation of 'bumper
to bumper' scale,
resembling small oyster shells....these are the Mama scales. Young scale crawlers emerge from
beneath these 'turtle shells.' Dormant oil sprays, properly used, will
provide good control of this insect pest, and be less harmful to the
environment than most other pesticides. Read and follow label
directions, they are there to help.
can be seen emerging in July
on this Magnolia in Pennsylvania
Video of Maple Scale
Dormant season: Horticultural oil applied in early spring. Growing season: Contact insecticides will kill crawlers.