Although this species is well established, damage has been lower in subsquent years. Description and life cycle Western flower thrips, formally limited to western North America, has become virtually cosmopolitan since the 1970s. This species is a key pest in the greenhouse production of flowers and vegetables. Although oviposition by this species causes a condition called pansy spot on some apple varieties in the west, it has not been shown to injure apples in the east. In addition to direct feeding injury, it transmits tomato spotted wilt virus.
Males are about two-thirds the size of females and generally lighter in color.
Larvae resemble adults but lack wings and are smaller. This species is difficult to distinguish from less injurious species of flower thrips. May. Populations build up on crop and weed hosts throughout the season, peaking in the summer. Generation time in summer conditions is about two weeks. Apparently drought conditions and above-average temperatures, such as occurred in Adams County in 1991, can result in damaging populations of this thrips.