Horticulture Principles and Practices

FIGURE 7–5
(Source: USDA)
Caterpillar of cotton bollworm.
FIGURE 7–6 Typical damage caused by a chewing insect pest
such as a cabbage worm. (Source: Photo provided courtesy of Oklahoma
Cooperative Extension Service, Oklahoma State University)
(a)
(b)
FIGURE 7–7 Sucking insects: (a) aphids and (b) mealybugs. (Source: Photos provided courtesy of Oklahoma Cooperative Extension Service, Oklahoma State
University)
226 Chapter 7 Biological Enemies of Horticultural Plants
Boring. The chewing mouthparts of borers are used to bore channels into
succulent tissue—stems, fruits, tubers, and seeds. Examples of pests that bore
into plant parts are corn borers and white grubs.
Leaf mining. Unlike borers, which bore directly into the tissue, leaf miners only
tunnel between epidermal layers.
Root feeding. Root feeders damage plants from below in the soil by chewing roots
and other underground structures. Examples are white grubs and wireworms.
Sucking and Piercing Insects Sucking and piercing insects puncture the plant part
on which they feed in order to suck out plant fluids. Examples of such insects include
aphids, scales, mealybugs, thrips, and leaf hoppers. Insects in this group are often
small in size (Figure 7–7). Even in their adult stage, they can be microscopic, making
them difficult to readily detect and control.
Their effect is often recognized as curling up or puckering of leaves (leaf distortion)
or bleaching of leaves. Sucking and piercing insects also damage fruits. They
are often found on the undersides of leaves. Certain sucking insects may inject toxins
into the plant in the feeding process. Another characteristic of damage caused by