Page 125 - ORNAMENTALES DEL TRÓPICO

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identiFication and management oF ornamental Pests

woody plants and trees are subject to borer attack. The type (location, shape) of the tunnel or
emergence hole can sometime help determine the type of insect causing the damage. Most

borers attack unhealthy or stressed plants or trees. The preferred and most effective manage-

ment practice is to keep plants and trees healthy.

f. Gall makers
Galls occur on a wide variety of plants. These growths may be the result of fungi, bacteria,

nematodes or mites, but insects are the prime cause. Gall-forming insects include aphids, phy-

lloxerans, psyllids, midges, and wasps. Plant galls are abnormal growths of plant cells in respon-

se to the insect. Insects can often be found inside the gall. Each gall-forming insect produces

a gall that is characteristic of that particular insect. Gall can vary greatly in their appearance

and size. They are most commonly found on the stems and leaves but also occur on trunks,

flowers, and roots.

g. Mites

Mites, although not insects, are treated very much like insects. There are three major groups

of mites that attack ornamental plants: spider mites, false spider mites (or flat mites), and erio-

phyid mites. Spider mites are the most common. Mites attack a large variety of plants. All mites

have piercing mouthparts in which they remove sap from plant tissue ultimately causing a small

chlorotic spot at each feeding site. Continued feeding causes a stippled, bleached effect, and
later the leaves turn yellow, gray or bronze. Complete defoliation may occur if the mites are

not controlled. Spider mites produce webbing which is sometimes the first sign of an infes-

tation. Eriophyid mite feeding may result in galls, blistering, discolored and stunted terminal

growth, and discolored buds, floral parts and leaves.

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