There are more
different types of insects in the world than even
the entomologists can count accurately. For the home
gardener, perhaps it is more important to divide
insects into categories based on how they feed or
inflict damage to their plants. Knowing how an
insect feeds can help to identify that insect which
is the first step on the way to determining what, if
any, control measures would be effective.
Generally, landscape
insect pests can be divided into the following
groupings:
1.
Chewing Insects - These
critters have mouth parts that are capable of taking
a bite out of a leaf, root or stem. The sign that
they have been feeding will be holes or missing
plant parts. Tops among the chewing insects would be
the caterpillars, beetles and plant bugs.
2.
Sucking Insects - This
category of insects live by sticking their proboscis
(snout) into the plant tissue and then they suck out
the nutrient rich sap. In large numbers, they may
pull out enough sap to cause severe stress to the
plant. Key sucking insects would include
aphids,
leafhoppers and a relative of spiders called
spider
mites.
Often, these insects
suck out the
chlorophyll as they feed causing the
plant to turn yellow with a "stippled" effect.
Another sign is often the appearance of a black
covering on leaves called sooty mold. As the insects
feed, their droppings which consist of a sweet,
sticky material, drops onto the leaves below. This
material called
honeydew is what the sooty mold
fungus uses as its food.
3.
Boring Insects - No
these are not insects that lack in social graces.
Rather, these are critters that spend their immature
stage (larvae) chewing on the inside of the plant.
Borers do their damage by interrupting the water
carrying vessels in the stems. Ones such as the
Emerald Ash Borer, that bore near the surface, just
beneath the bark in the
cambium layer can actually
kill the tree. Fortunately, most borers tend to
attack old, stressed trees and rarely go after
young, healthy ones.
