Thrips:
Western Flower Thrips - Frankliniella occidentalis (Pergande)
Tobacco Thrips - Frankliniella fusca (Hinds)
Onion Thrips - Thrips tabaci Lindeman

Dr. Randy Hudson, Extension Entomologist, The University of Georgia, Department of Entomology, Tifton, GA 31793
Dr. David Adams, Extension Entomologist, The University of Georgia, Department of Entomology, Tifton, GA 31793

Order Thysanoptera: Family Thripidae

Description: Several thrips are economically important in Georgia. The western flower thrips and the tobacco thrips are two very destructive species. Adult thrips are usually less than 2.0 mm in length. The adult western flower thrips is yellow or yellow-orange; the tobacco thrips adult tends to be dark brown to black in appearance. Adult thrips have two pair of fringed wings. Larvae are very small at about 0.25 mm in length. They are white or cream-colored during the first instar, turning more straw-colored during later stages. There is a pupal stage that occurs in the soil. Hosts: Thrips have a wide host range. Most vegetables, agronomic crops, ornamentals, and weeds have one or more thrips species that may attack them. Damage: Thrips cause noticeable damage to seedling stage plants. They rasp the leaves and terminal buds with their sharp mouthparts and feed on the escaping juices. Leaves may turn brown on the edges, develop a silvery color, and may become distorted and curl or cup upward. Early, moderate to severe thrips injury can delay maturity. The main seedling thrips in Georgia are the tobacco and onion thrips.

Damage to cotton seedling Photo by : Barry Freeman, Auburn University

Western flower thrips Photo by: Jack Reed

The western flower thrips feeds on the blooms and fruit of many plants. They cause various types of mechanical injury to the fruiting structures. These include pits, buckskin, black specks, raised blisters and cat-facing.

Western flower, tobacco and onion thrips transmit tomato spotted wilt viruses on several crops. This is the more significant damage caused by thrips. Some of the crops affected severely by TSWV are tobacco, peanut, tomato and pepper.

Life Cycle: Thrips have a unique life cycle. The adult lays her eggs in plant tissue. The larvae hatch and enter two (maybe more) instars before entering the prepupal and pupal stage in the soil. The pupae emerge as winged adults and migrate back to the plants or out of the field. The entire cycle from egg to adult requires from 12 to 16 days.

Control: Thrips can be controlled with insecticides even though western flower thrips is tolerant of several insecticides and is the most difficult one of the three species to control. Each crop has different treatment thresholds.

In: Roberts, P. M. and G. K. Douce, Coordinators. 1999. Sucking Insects. A County Agent's Guide to Insects Important to Agriculture in Georgia. Univ. of GA, Col. Ag. Env. Sci., Coop. Ext. Serv., Tifton, GA USA. Winter School Top Fifty Agricultural Insect Pests and Their Damage Sessions, Rock Eagle 4-H Ctr., Jan. 20, 1999

Selected References and Suggested Readings