Pest profile

Greenhouse Thrips

Heliothrips haemorrhoidalis · Thysanoptera: Thripidae[3]

Greenhouse thrips are tiny dark-brown thrips that feed on the leaves of azaleas, viburnum, ferns, orchids and many other ornamentals, leaving them silvery or bleached and speckled with dark excrement.[1][2]

Greenhouse thrips adult, dark-bodied with pale wings, on a leaf
Greenhouse thrips adult, dark-bodied with pale wings, on a leaf. (c) Saryu Mae 前 朝琉, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are about 1/16 inch long, dark brown to black with a lighter tail end, pale yellow legs and narrow, pale wings.[1][2]
  • Larvae are white, then yellowish, with red eyes, and often carry a dark droplet of excrement at the tip of the abdomen.[1][2]
  • Damaged leaves look silvery or bleached and may yellow and drop; dark specks of excrement dot leaves and fruit.[1]

Where it lives

In the US it lives outdoors in central and southern Florida and southern California and in greenhouses everywhere, sometimes escaping in warm months.[2]

Biology and life cycle

It reproduces without mating, and males are seldom seen; females insert single, white, banana-shaped eggs into leaves or fruit.[1][2]

Two larval stages are followed by prepupa and pupa stages that stay on the plant rather than dropping to the soil.[1][2]

Damage and signs

  • It attacks over 100 hosts, including azalea, begonia, croton, cyclamen, ferns, fuchsia, grape, orchids, palms, roses and viburnum.[1]
  • It usually injures inner leaves, neither the youngest nor the oldest, and attacked fruit turns brown, cracked and sunken.[1]

Health risk

None to people or pets.[1][2]

Control

Biological control

The predatory bug Orius insidiosus and the predatory mite Neoseiulus cucumeris, sold by biological control suppliers, are relatively effective.[1]

Pesticides

Contact sprays such as horticultural oils, soaps and pyrethrins don't kill eggs inside leaves, so repeat applications about every two weeks may be needed.[1]

Common questions

Why are my azalea leaves silvery with black specks?
Greenhouse thrips feeding bleaches leaves and leaves dark specks of excrement.[1]
Why do thrips come back after spraying?
Eggs inside the leaves survive contact sprays and hatch up to two weeks later.[1]
Do greenhouse thrips live outdoors?
In the US, mainly in central and southern Florida and southern California.[2]

Sources

  1. NC State Extension, “Greenhouse Thrips.” content.ces.ncsu.edu/greenhouse-thrips (accessed 2026-10-15)
  2. University of Florida IFAS Extension (Featured Creatures), “Greenhouse Thrips, Heliothrips haemorrhoidalis (EENY-075).” ask.ifas.ufl.edu/publication/IN232 (accessed 2026-10-15)
  3. iNaturalist, “Heliothrips haemorrhoidalis taxon page (order and family).” www.inaturalist.org/taxa/330694 (accessed 2026-10-06)

Updated 2026-10-15. Built from sourced records. Spot an error? Tell us.