Thrips Control

Description

Thrips are straw-colored, elongated insects. Adults have narrow, fringed wings, and nymphs are wingless. they can move rapidly and prefer to shelter in crevices and folds in flowers and foliage. Thrips damage plants by feeding on leaf and flower tissue, leaving a silvery appearance. They also lay eggs in leaves and flower tissue and in young developing fruit (such as cucumbers). This causes distortions in fruit and in the growing points. On tomatoes, thrips feeding causes 'ghost rings' on the fruit. Western Flower Thrips can also transmit Tomato Spotted Wilt Virus (TSWV), which is lethal to tomatoes and some ornamentals. Western Flower Thrips (Frankliniella occidentalis) is found in both vegetable and ornamental crops. Onion thrips (Thrips abaci) is more common on vegetable crops.

Life Cycle

Both the WFT and Onion thrips have similar life cycles. The overall life cycle of Western flower thrips takes 21 days at 72F. Females lay eggs in leaf tissue. Each female lays 6-10 eggs per day over her life span of 4-5 weeks. The eggs hatch in five days at 72F. The nymphs feed on plant tissue for 8-10 days, then drop to the ground to complete development in protected sites on the floor or soil. Thrips have an immobile stage, similar to pupil stage, called a pseudo-pupa which takes 7-10 days. When adults emerge they fly to upper parts of the plants and the females begin laying eggs after a day or two.

Thrips Identification

Please note that there are many species of thrips, and the specific thrips species that you commonly deal with will impact how you manage them. Thrips species that have a soil-dwelling pupal life stage will be suppressed by soil-dwelling predators and parasites. Foliar-bound thrips species will not be suppressed by soil-dwelling predators and parasites and the focus should be on foliar predators.

Foliar bound thrips:
- Common blossom thrips (Frankliniella schultzei Trybom)
- Grass thrips (Anaphothrips obscurus Muller)
- Pointsettia thrips (Enchinothrips americanus Morgan)

Soil-pupating thrips:
- Bean thrips (Caliothrips fasciatus Pergande)
- Florida Flower Thrips (Franliniella bispinosa Morgan)
- Melon thrips (Thrips palmi Karny)
- Tobacco thrips (Frankliniella fusca Hinds)
- Western Flower Thrips (Franliniella occidentalis Pergande)
- - Thrips parvispinus (Thrips parvispinus Pergande)
- *Onion thrips (Thrips tabaci Lindeman)
- *Chilli thrips (Scirtothrips dorsalis Hood)