Aphids
Aphid species usually either attack plant leaves or aggregate on the growing stem tips. Pruning often eliminates tip feeders such as green peach aphid. Aphids also have many effective natural enemies including ladybug beetles, lacewings, parasitoids, and diseases. Pesticides can eliminate the natural enemies in nurseries. These natural enemies are usually very abundant in the landscape and some are commercially available. Research on the use of commercially available species has shown mixed results. Lacewings seem to have some promise if suitable methods of release can be developed. Different species of natural enemies display myriad habits relative to host range, host plants searched, response to prey densities and ability to control aphids. The best strategy is to encourage a complex of natural enemies by increasing plant diversity, maintaining cover crops, or designing landscapes which provide alternate hosts, flowers, shelter, etc. The recent introductions in Georgia and Florida of the lady beetles, Coccinella septempunctata and Harmonia axyridis, from Europe and Japan, respectively, have reduced aphid populations on many woody plants, including crape myrtle.
Borers
There are many different families and species of borers that usually are associated with stressed or injured plants. Once these insects gain entrance to the plant, they are very difficult to control. Biological controls are usually not effective because, once the borer is inside the plant, the damage is done.
Caterpillars
These immature moths or butterflies have many natural enemies that often keep them in check under natural conditions. Caterpillars may be attacked by insect parasitoids and predators, nematodes and pathogens. Bacillus thuringiensis is a bacteria that is commercially available in many varieties to control caterpillars and other insects. It is compatible with other natural enemies and safe to humans. Neem products also may have anti-feedant effects on some caterpillar species.
Lace Bugs
Lace bugs have a few known natural enemies including wasps that parasitize the eggs and predaceous mirids. Little is known about the natural enemies of lace bugs.
Leafminers
Leafminers are often kept in check by natural enemies, mainly parasitoids. Conventional pesticides disrupt these biological controls and leafminers are often induced pests. Use selective pesticides to conserve natural enemies.
Scales
Armored and soft scales have many natural enemies that often keep them in check. Scales have often been the target of classical biological control. The vedalia beetle, Rodalia cardinalis, was introduced around the turn of the century in California to control cottonycushion scale in citrus. Chilocorus kiwanae was recently introduced throughout the southeastern U.S. to control euonymus scale. Use of conventional pesticides often destroy natural enemies on scales and disrupt biological control. Parasitoids are abundant on scales and male and female scales may be attacked by different species of parasitoids.
Spider Mites
Nursery: Many species of mites occur in nurseries throughout Florida. There are many native predatory mites and insects that attack spider mites. Due to heavy pesticide use, these beneficial species are often eliminated from production areas. Reduction in pesticide use, use of biorationals and tolerance of a higher level of damage are the first steps to increasing natural biological control of mites. The acaricides Vendex and Ornamite and many fungicides are not toxic to predatory mites. Several species of native and exotic predatory mites are available commercially. Recommendations as to host plant, release rate and timing, species to use, etc. have not been adequately determined. However, some growers and industry representatives are experimenting successfully with predatory mites. The difficulty of managing predator mites will require a great deal of knowledge and trial and error to use successfully. Research in this area is in progress and successes in specific situations have been achieved. Any experiments with biological controls should have an untreated area for comparison. Insect and mite populations are notorious for decreasing without apparent reason. Results can be very misleading without control plots.
Landscape: Mite pests found in the nursery are also found in the landscape, but usually are kept in check by native natural enemies. Most mite pests are native species and a classical biological control approach using several species of exotic predatory mites has not been successful. The tremendous variation in the life history requirements of the natural enemies and similar variation in habitats throughout the state diminish the present potential of this approach. Growers should conserve the natural enemies naturally present by using biorationals within the context of IPM.
Thrips
Thrips have natural enemies which are predominantly predators. Several species of predatory mites that prey primarily on thrips are available commercially. There are predaceous thrips which prey on other thrips and softbodied insects and mites. As a rule thrips on woody plants outdoors are not a problem. However, they inhabit indoor or greenhouse flower blooms and are often a nuisance. Conserve CS is a good thrips insecticide that is compatible with beneficial insects.
Whiteflies
Whiteflies have many natural enemies that often regulate their numbers to low levels. Parasitoids can be very effective. Practice IPM and use biorationals to conserve native natural enemies. Many species of whiteflies have been or are the target of classical biological control. Growth regulators such as Enstar II, Distance IGR, or botanicals such as Neem products, and oils and soaps appear compatible with parasitiods.