Frankliniella occidentalis



Conservation status

Not Assessed

First reported in the wild



Invasive species - risk of High Impact

Irish status

Present in the Wild

Introduction pathways - 1

Transport Contaminant

Introduction pathways subclass - 1

Parasites on plants

Invasive score


NAPRA Ireland risk assessed


Species Biology


Tiny, slender, phytophagous (eat plants) insect with narrow fringed wings, with a highly variable morphology, adult females colours range from white to yellowish orange to nearly black size 1.6-1.7 mm long, with pale adult males 1.2–1.3 mm long, nymphs (larvae) are yellowish-white (Kirk & Terry, 2003; Roques, 2006).


Major pest of a wide range of agricultural crops including pepper, cucumber, apricot, chrysanthemum, plum, roses and strawberries (EPPO, 2015), as well as responsible for transferring a number of plant disease (Kirk & Terry, 2003).


Constructed, industrial or other artificial habitats


Parthenogenic (can reproduce from unfertilised eggs), with males emerging from unfertilised eggs, 12-15 generations per year, with the life cycle duration being temperature dependent lasting from 15-41 days (Roques, 2006).

Pathway and vector description

Originally native to the western North America, from Mexico to Alaska, it spread to Holland in 1983 and from there spread across Europe and Asia at a rate of ~229km/year, suggesting human mediated dispersal rather than natural spread (Kirk & Terry, 2003). Distribution appears to have been largely unchanged until the 1960s and the rapid and wide spread is thought to have been as the result of a insecticide resistant strain developing (Kirk & Terry, 2003).

Mechanism of impact

Grazing/Herbivory/Browsing, Disease transmission

Broad environment


Habitat description

Feeds on a wide range of species, unlikely to be able to survive out of doors overwinter in Ireland, it is largely found in greenhouses, though Irish records are based on the 1980s (Dunne & O'Connor, 1989).

Species group


Native region

North America


World distribution(GBIF)

Irish distribution

Established - Widespread. The European and Mediterranean Plant Protection Organisation classify this species as "Present and Widespread" in Ireland but this assessment is based on information form 1993 (EPPO, 2015). Found in greenhouses, as they require high humidity and temperature (Fatnassi eet al., 2015) the current status of this species in Ireland is unknown, though it is certainly present.

Native distribution

Originally native to the west of North America from Mexico to Alaska (Kirk & Terry, 2003).

Temporal change

Date of first record category


Fifty year date category


Records submitted to Data Centre in 2021

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How can you help

Report any sightings to the National Biodiversity Data Centre.

Further information

Delivering Alien Invasive Species In Europe (DAISIE) project the western flower thrip as one of the 100 Worst Invaders in Europe.



EPPO (2015) PQR EPPO Database on quarantine plants. European and Mediterranean Plant Protection Organisation[Online]. Dunne, R., & O'Connor, J. P. (1989). Some insects (Thysanoptera: Diptera) of economic importance, new to Ireland. The Irish Naturalists' Journal, 63-65. Fatnassi, H., Pizzol, J., Senoussi, R., Biondi, A., Desneux, N., Poncet, C., & Boulard, T. (2015). Within-Crop Air Temperature and Humidity Outcomes on Spatio-Temporal Distribution of the Key Rose Pest Frankliniella occidentalis. PloS one, 10(5), e0126655. Kirk, W. D., & Terry, L. I. (2003). The spread of the western flower thrips Frankliniella occidentalis (Pergande). Agricultural and Forest Entomology, 5(4), 301-310.