NC State Extension Publications

Description and Biology

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The greenhouse thrips, Heliothrips haemorrhoidalis, is dark brown with the tail end much lighter. The legs tend to be uniformly yellow, and the wings are paler and narrow. The antennae are slender with a characteristic needle-like tip. The mature adults are about 1/16 inch long. Females insert very small, white, banana-shaped eggs into leaves. From eggs hatch tiny, white larvae. The next larval stage is yellowish. Both stages have red eyes and often carry a dark fecal droplet at the tip of the abdomen. Second larvae molt into prepupae that soon molt into pupae. These stages are yellowish with red eyes and do not move about freely. Pupae have longer wing pads, and the antennae bend back over body. Pupae darken with age. Unlike other species of thrips whose prepupae and pupae drop to the soil, at least some greenhouse thrips pupae remain on infested leaves. Each female inserts 25 to 50 eggs in leaves. Under optimum conditions the time for development is 17 to 20 days for the eggs, about 13 days for the two larval instars, and about 5 days for the prepupal and pupal stages. The adults can live 7 weeks on plants growing in the greenhouse. All stages can be found throughout the year in greenhouses. Greenhouse thrips move relatively slowly and rarely fly. They prefer a cool, shady, and fairly moist atmosphere.

Greenhouse thrips

Greenhouse thrips are dark brown to almost black with paler wings and legs.

Immature greenhouse thrips

Immature greenhouse thrips are usually white or yellowish.

Host Plants

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Greenhouse thrips attack over 100 hosts, principally greenhouse and ornamental plants, but also a few crops and tropical plants. Some of the hosts are azalea, begonia, croton, cyclamen, ferns, fuchsia, grape vines, orchids, palm, rose, and viburnum. This thrips feeds almost entirely on the foliage, and large populations cause severe damage. Greenhouse thrips usually injure inner leaves, neither the youngest nor the oldest, and fruit. Damaged leaves appear silvery or bleached and, if the damage is severe enough, turn yellow and drop. Fruit that has been attached is brown, cracked, and has noticeable sunken areas. Dark spots of excrement are often noticeable on the leaves and fruit.

greenhouse thrips can cause severe damage

If uncontrolled by natural factors, greenhouse thrips can cause severe damage.

leaf has any nutrients left to sustain these greenhouse thrips

It's hard to see that this leaf has any nutrients left to sustain these greenhouse thrips.

Residential Recommendations

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Two predators are relatively effective for the biological control of thrips: Orius insidiosus (the insidious plant bug) and Neoseiulus cucumeris (a predaceous mite). These beneficial arthropods are available from biological control suppliers. Because thrips insert their eggs into their host plant, a contact insecticide may kill all the exposed thrips but may not kill their eggs. Depending upon the insecticide, thrips eggs hatch into new, tiny thrips as long as two weeks after treatment so the infestation may have a second wave. Insecticides such as horticultural oils, soaps, pyrethrin and perhaps neem extracts have little residual life after they are sprayed onto a plant, so repeated applications at two week intervals might be necessary for complete control. Orthene and imidacloprid are two systemic insecticides that would last in the plant long enough to kill any newly-hatched larvae that as eggs escaped the first application. Several formulations of imidacloprid are available for residential landscape use (The active ingredient of any pesticide is listed on the front label although usually in very small font close to the bottom.). Pyrethroids are in a third group of insecticides useful for thrips suppression. When used as directed, pyrethroids are very toxic to insects but are not particularly hazardous to humans and pets (other than fish—avoid using pyrethroids around pools, ponds, and streams). They have a long residual life on the plant after application and would last long enough to suppress newly-hatched thrips larvae. The active ingredient of all pyrethroid insecticides end in "thrin" such as bifenthrin, lamda-cyhalothrin, or permethrin. All of these insecticides listed above can be purchased at big box stores, nurseries, and plant centers.

Other Resources

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For assistance with a specific problem, contact your local Cooperative Extension Center.

This Factsheet has not been peer reviewed.


Professor Emeritus
Entomology & Plant Pathology

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Publication date: June 5, 2020
Revised: June 5, 2020

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