Thrips are insects in the order Thysanoptera. Western flower thrips, Frankliniella occidentalis, is one of several thrips that can be damaging to ornamental crops. During the summer months when nearby crops are harvested, large migrations of thrips into productions areas can occur. These populations of thrips can be large enough to cause extensive damage to susceptible plants, including terminal losses and stunting. We've had reported damage from azaleas, Amelanchier, cherries, chrysanthemum, crabapple, hawthorn, gerbera, laurel, Norway, red, sugar and Japanese maples, mountain ash, purple leaf plum, and viburnum
Identification
Thrips of California 2012 Lucid key is a very robust key with many of thrips that might also occur in the PNW. Best to use if you have a slide mounted specimen.
Western Flower Thrips
North Carolina State University's Insect Notes: Western Flower Thrips
The Integrated Plant Protection Center, Oregon State University: Western Flower Thrips has information and phenology useful for Oregon growers.
UC IPM Online Pests in the Landscapes and Gardens: Thrips has some very nice information on monitoring and management.
From UC Riverside - Western Flower Thrips in Greenhouses: A Review of its Biological Control and Other Methods. An absolutely fantastic guide for those interested in biological control.
Pacific Northwest Plant Disease Management Handbook has great information on managing two key viruses vectored by thrips: Impatiens -- Impatiens Necrotic Spot; Greenhouse Plants, Ornamental -- Impatiens Necrotic Spot
Canas, L. 2016. Managing Thrips Resistance to Insecticides. Greenhouse Product News. <2 June 2016>
Cal Ag's article on IPM Works in California Greenhouse Cut Roses discusses thrips management. A PDF with images can be downloaded from the site.
Poinsettia thrips (Echinothrips americanus)
Original publication: 8/3/2004
Latest publication: 6/2/2016
Author: R.L. Rosetta, Extension Nursery Integrated Pest Management, Department of Horticulture, Oregon State University
Closeup of thrips and feeding damage on new growth of Japanese maples
Closeup of thrips feeding
Leaf cupping and blackening of leaf edges on hawthorn from thrips feeding
Two thrips feeding in hawthorn terminal causing tissue blackening and necrosis
Tip death and leaf distortion on hawthorn from thrips feeding
Closeup of thrips damage on new growth of Japanese maples
Dramatic effect of cultivar on susceptibility - 'Bowhall' maple on left.
Thrips damage on English laurel
Stunting and distorted growth in 'Kwanzan' cherry
Severe thrips damage on red maple.
Thrips damage on plum terminal
Misshapenleaves and blackened tissue on sugar maples
Terminal distortion and blackening on sugar maple from thrips feeding
Thrips larva on plum terminal leaf
Thrips on new growth of Japanese maple
Adult western flower thrips on red maple terminal
Thrips damage on viburnum terminal.