The Rockdale Gardener

Gardening Posts From Rockdale Cooperative Extension

Beneficial Insects, Spiders and Mites

beneficial insects

NEW Beneficial insects publication from UGA page 1

The most numerous form of life on earth is the insect and they take care of some of the most basic chores of the natural world. Our beneficial six-legged friends perform processes such as organic matter decomposition, soil aeration, and pollination. They also help to control harmful insects that damage crops in a variety of ways. By employing the pest control philosophy known as IPM or Integrated Pest Management, we can identify and protect beneficial insects while controlling harmful ones.

Healthy Plants = Happy Plants

The first step to effective pest control is growing healthy plants. Providing plants with good soil, proper moisture, and adequate sunlight keeps them growing vigorously. When plants are actively growing, they produce natural insecticidal chemicals and resist pest pressure. Preventing stress during the transplant process is also important. When choosing plants, look for insect ‘resistant’ plant materials. Native plants are better suited to the southeast, and often perform better and are more pest resistant than exotics.


beneficial insects 2

NEW Beneficial insects publication from UGA page 2

Scouting, the inspection of plants for pests, is the basis of good Integrated Pest Management. It should be performed weekly during the growing season. A good scout must be able to recognize the good guys from bad guys. Check the undersurface of leaves for aphids, scale insects, lacebugs, whiteflies, and spider mites. Look for signs of damage such as yellowing, chlorotic spots, curled, distorted leaves, wilting, and black sooty mold on the upper surface of leaves. Remember, good guys are often solitary while bad guys are often in groups of hundreds or thousands.

You can also use scouting devices to help with inspections. One type of scouting device is the white paper test. Tap flowers over a sheet of white paper to dislodge insects like thrips. Another device is a sticky trap which can easily be made with yellow and blue plastic plates. Simply coat them with a tacky substance like spray glue or oil, and hang them near flowerbeds and shrubs. Whiteflies, aphids, and thrips will be attracted to the traps and become ensnared. Count the number of insects you trap and decide if action is needed. Sticky tape makes a good monitoring device, too. Simply wrap it around the stems of shrubs and flowers to monitor scale crawlers, spider mites, and other crawling insects.

Consider Your Thresholds

The grower decides damage thresholds. Economic and aesthetic thresholds may differ depending on the plant type, the pest involved, and the use of the plant. Economic thresholds are based on the amount of monetary loss a grower can stand before control becomes necessary. Aesthetic thresholds are based on how much damage an ornamental can sustain before control measures must be implemented.

Use Less Toxic Controls

A water hose is one of the least toxic devices you can use to get rid of pests. Aphids, lace bugs, and spider mites can all be

NEW Beneficial insects publication from UGA page 3

NEW Beneficial insects publication from UGA page 3

removed with a heavy stream of water. These pests become disoriented and find it difficult to find their way back to the plants. If done several times, this can be an effective control method.

A second effective and non-toxic control option is to pick insects off by hand or prune them out. This method is effective for larger pests such as bagworms, tent caterpillars, and fall webworms. Destroy the insects, or bag them and place them in the trash.

The use of biorational insecticides is a third less toxic control. Soaps, horticultural oils (Dormant, Summer, and Superior), naturally derived botanical insecticides like neem, and insecticides derived from naturally occurring bacteria (Bacillus thurengiensis products like Bt and Dipel) all provide good control without polluting the environment.

     The Good Guys        The Bad Guys  
Parasites Sucking Insects
▪    Parasitic wasps ▪    Whiteflies
▪    Parasitic flies ▪    Aphids
▪    Scale insects
Predators ▪    Lace bugs
▪    Spiders and mites ▪    Spider mites
▪    Big-eyed bugs ▪    Thrips
▪    Lacewings
▪    Praying mantids Chewing Insects
▪    Syrphid flies

▪    Ground beetles

▪    Caterpillars (bagworms, tent caterpillars, webworms)
▪    Lady beetles

▪    Predatory true bugs (spined soldier bugs, damsel bugs, minute pirate bugs, assassin bugs, big-eyed bugs)

▪    Beetles (Japanese beetles, leaf beetles, flea beetles)

Encourage Beneficial Insects

Beneficial insects can be encouraged in a number of ways. Start by planting alternative food sources that provide pollen and nectar. Daisies, Queen Ann’s lace, yarrow, alyssum, golden rod, alfalfa, clovers, and vetches will all attract beneficial insects.

Water sources attract beneficial insects as well. Birdbaths, temporary puddles, small dishes of water, and dripping water can be easily installed in any garden. Remember to replace the water every few days to avoid mosquitoes and to keep it attractive. Place small ‘perches’ in water sources to help beneficial insects access the water.

The final way to encourage beneficial insects is to provide them with shelter. Areas that are left undisturbed benefit insects. Allow forest edges to grow wild and do not mow open areas unnecessarily. Create perennial flowerbeds that will flower all season by staggering different species throughout the bed. Hedgerows also provide beneficial insects with shelter.