Some thrips are pests while others, like the black hunter feed on fungal spores, pollen, mites and insects.
Adult thrips have narrow wings and measure 1/20" long. Nymphs are shaped similar to adults, but without the wings. Thrips colors varies and range from yellow, dark brow, semi-clear to red-orange shades.
Unlike spider mites and aphids, thrips prefer to feed in hidden areas like inside flowers, buds, or curled leaves; making them difficult to notice.
Alert Gardeners will notice signs of discolored leaves, distorted tissue, or specs of feces on spotted foliage. Thrips shows signs of infestation similar to other pests like plant bugs, lacewings and mites; making identification more complex.
Experienced Gardeners will wait before applying any control method to make properly identify the pest to a high degree of certainty. Monitor plants carefully and watch the pests' behavior, body type and consider the type of plant affected when trying to identify thrips. Onions, avocado, citrus, beans, garlic, peppers and others may be affected by thrips.
Most experienced Gardeners, however, may resort to hiring an expert to address the problem. Thrips species can only be identified by an expert. Identifying the thrips species is important if you are using predatory insects to control the problem.
Species - thrips
There are various species of thrips, including the avocado, bean, citrus, geenhouse, western flower thrips, cuban, toyon, and the onion thrips.
Host plants of thrips
Herbaceous ornamentals, vegetables, avocado, citrus, perennial ornamentals, some fruit trees, beans and sometimes other legumes.
Thrips life cycle
Thrips can have several generations a year (eight or more). Thrips life cycle from egg stage to adulthood may be completed in as little as 2 weeks during warm weather.
Thrips may cause tiny scars on leaves and fruits, commonly referred to as stippling. They may stunt the plant's growth and development. Damaged leaves may become distorted or papery in texture.
Depending on the type of plant, foliage may fall prematurely, become discolored, petals may show break in color, appear pale or dark and scarring on fruits may occur.
Newly developing plant tissue are a thrips favorite. Thrips can spread for long distances. Thrips spread by floating with the wind or by transplanting infested plants in different locations.
Use a combination, when necessary, of predatory insects and an insecticide with a mild insecticide such as neem oil. Always aim for environmentally friendly control measures.
Viruses - thrips
Viruses transmitted by thrips, such as the impatiens necrotic spot virus or tomato spotted wilt virus can only be accurately diagnosed by testing the plant in a lab or by using specialized test kits.
Biological Control - thrips
Plant-feeding thrips can be controlled using a number of benefical insects like predaceous mites, predatory thrips, minute pirate bugs and predatory sixspotted bug.
Beneficial insects and mites are known to help control certain plant-feeding thrips, however, their effectiveness has not been researched. Preserving the population of beneficial insects, controlling dust and avoiding toxic, presistent pesticides is the most effective way to impliment biological control of thrips.
Predators --> Prey
Lacewings, minute pirate bugs, mites, tiny wasps, species-specific parasites: Many thrips species
Predatory mites: Citrus thrips
Predatory thrips: Avacodo, greenhouse thrips
Minute pirate bugs: Cuban laurel thrips
Sixspotted thrips: Primarily prey on mites, but feeds on some thrips
nymphal endoparasitic wasp: Greenhouse thrips
Chemical Control - thrips
Insecticides are only partially effective and should be used in combination with beneficial insects. In such instances, a low toxicity insecticide such as neem oil, insecticidal soaps and pyrethrins should be used. This control measure will only offer temporary reduction of thrips population if the infestation is caught in its early stage.
This article courtesy of www.hydroponicsearch.com