• Topics: Entomology and Nematology  | Nursery Insects and Mites  | Landscape Pests  | Landscape Insect Pest Management  | Ornamentals (IMG -- Vol.1, Ch. IV)  | Buss, Eileen A 

Insect Management on Landscape Plants¹

The urban landscape is a diverse area that includes many different plants, ranging from annual foliage plants to perennial trees and shrubs. It is a complicated system to manage because, unlike in agriculture, plantings are fragmented and separated by developed areas. Each home or commercial area is also maintained differently, and the owners or managers have different goals for their landscapes. Some may desire a perfect, well-manicured look, while others may prefer a more natural appearance that requires less work to maintain.

A lot of insects, mites, and other insect-relatives feed on ornamental landscape plants. Many are harmless, some are beneficial, and some are pests. Some pests may need immediate control, especially if present in great numbers, but others may not be worth the time, effort, or cost of control. Feeding by pests may cause real damage to the plants or just make the plants look bad or unhealthy. However, insects are only one of many potential causes for unhealthy-looking plants. Diseases, nematodes, drought, nutritional disorders, and improper chemical applications can also be damaging. Correct identification of the problem can save money and prevent unnecessary chemical use. After the pest is correctly identified, information can be found on its life cycle, food preference, and habits. It is important to understand these things to properly time any corrective measures.

Scouting or monitoring for damage or pests is an important part of plant health care. Examine plants weekly in the spring, summer and fall. Exactly how to monitor for each pest depends on where the insect lives or feeds. Look for pests under a few leaves and the stems or branches of each plant. If thrips or mites are suspected, hold a sheet of white paper under the leaves or flowers and shake the plant. Watch for moving specks on the paper and place them into a small jar or vial of rubbing alcohol for identification. Use a hand lens (10 or 15X) or magnifying glass to find tiny insects or mites on the foliage.

Pest Management on Ornamentals

Several options exist for managing insects and mites on ornamentals without the use of pesticides. These options include handpicking, knocking, or hosing pests off plants with water, and then destroying the pests. Removing infested plants or plant parts (e.g., pruning) and then burning or destroying them reduces the chance of pests moving among plants. Buying or using plants that are naturally resistant or tolerant to certain pests greatly reduces the need for future control. Any mechanical or cultural method that prevents or excludes pests from the plants should be attempted before using a pesticide.

However, if pesticide use is necessary to prevent economic damage to plants, consult Tables 1 and 2. Most of these pesticides kill by either contact with the insect or as a stomach poison. Some may also exert a fumigating or vapor action under certain conditions. Products should be selected that will effectively control the pests without injuring the plant, result in another pest outbreak, or kill beneficials and other non-target organisms. Before using a pesticide, consider the following points:

• Select the right product. Only use an insecticide that is recommended to control the target pest and is safe on the host plants.

• Use the label rate or recommended amount. Too little won't control the pest; too much is illegal. Read the container label carefully.

• Apply it correctly. Thorough coverage of the leaves (especially the underside), stems, and branches is essential. The pesticide must reach the area of the plant where the pest is feeding. Most failures to control pests result from incorrect applications, not product failure. The addition of a spreader-sticker to the spray mixture is suggested when spraying ornamental plants. Spreader-stickers help the pesticide to adhere to the leaves and improve coverage for better control.

Groups of Pests

Pests of ornamentals may be divided into five groups according to how they damage plants.

1. Insects with Piercing-Sucking Mouthparts. These insects have general straw-like mouthparts, which pierce the plant tissue and suck out the plant fluids. Examples: Scales, mealybugs, aphids, whiteflies, mealybugs, lace bugs, spittlebugs, thrips.

2. Spider Mites. These pests are not insects, but are closely related to spiders and scorpions. They suck plant fluids with their piercing-sucking mouthparts.

3. Foliage-Feeding Insects. They may feed on leaves or flowers. Examples: Caterpillars, beetles, grasshoppers, katydids.

4. Leafminers. These are very small larvae of flies, beetles, or moths that tunnel between the upper and lower leaf surfaces. Examples: Blotch leafminers and serpentine leafminers.

5. Borers. There are many species of insects which bore into the twigs or trunks of plants and trees. These are usually the larvae of moths or beetles. Examples: Pine bark beetles, sea grape borer, carpenterworm, dogwood borer.

For a list of key plants and their associated pests see List 1.

Additional Information

For additional information, please see these extension publications (http://edis.ifas.ufl.edu):

Beneficial Insects and Mites (ENY-276)

Insect Attractants and Traps (ENY-277)

Microbial Insecticides (ENY-275)

Natural Enemies and Biological Control (ENY-822)

Featured Creatures (http://entomology.ifas.ufl.edu/creatures)

Plant/Pest Guide

Part 1

Part 2

Part 3

Tables

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean.

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