by LUIS RODRIGUEZ
Florida faces many pests that harm crops and ornamental plants, including thrips, which cause significant economic losses. While they mostly overwinter, understanding thrips can help control them when they become active in warmer months.
Thrips Description
Thrips are tiny insects (1-2 mm) with piercing-sucking mouthparts that extract plant sap. While many species exist, only 1% are economically significant pests. They can infest various nursery or crop plants, reproduce quickly, and survive in diverse conditions (they tend to hide in small places). Adult thrips have wings, but larvae do not. Species of concern for Florida producers include western flower thrips, chilli thrips, weeping fig thrips, gladiolus thrips, and privet thrips.
Thrips Life cycle
Female thrips lay eggs on plant tissue, and the larvae begin feeding immediately after hatching. They go through two instars: instar #1 (1-2 days) and instar #2 (2-4 days). Then, they burrow underground for a prepupa (1-2 days) and pupa stage (1-3 days) before emerging as adults to feed on plants (30-45 days), restarting the cycle.
Thrips Plant Damage
Thrips damage varies by species but generally affects leaves, flowers, fruits, and shoots, reducing plant yield and economic value. They can transmit viruses like Necrotic Spot Virus (INSV), Chrysanthemum Stem Necrosis Virus (CSNV), and Tomato Spotted Wilt Virus (TSWV). Their feeding behavior damages plant tissue, causing silvering, bronzing, and distortions. Their excrement leaves dark spots, further decreasing plant value. Flower thrips, in particular, damage flowers, causing bud scarring, distortion, and discoloration.
Thrips Control
Thrips can be controlled using monitoring practices and Integrated Pest Management (IPM) for maximum effectiveness:
- Monitoring/Scouting – Scouting is essential for controlling thrips, as it helps prevent significant plant damage and potential financial loss. Producers should monitor for both the presence of pests and the damage they cause. Setting an economic threshold allows producers to determine acceptable pest levels and damage, guiding when control measures are necessary.
- Sanitation – Removing debris, including weeds, old plant tissue, and any other pest-harboring materials helps reduce thrips by eliminating potential hiding places that can spread them to your plants.
- Biological Control – This type of control relies on beneficial arthropods, such as lady beetles, mantises, spiders, wasps, and lacewings, that feed on thrips. When applying insecticides, select products that specifically affect thrips without harming these helpful organisms. This method is most effective during low or early infestations, as it may not control thrips or prevent plant damage in cases of heavy infestation.
- Physical Control – This type of control works by removing the thrips or excluding them. In greenhouses, using a mesh screen (<0.8mm) prevents their entry significantly, but airflow inside the structure must be considered.
- Chemical Control – The use of insecticides is effective for thrips control. Always follow label instructions and verify that it has thrips as a pest the product controls before the application. Ensuring thorough coverage in cracks and crevices is important since these are places where thrips may hide. Rotate pesticides with different modes of action to prevent resistance. It is recommended to apply in 5–7-day intervals to target thrips’ life cycles, although, as mentioned before, always follow label instructions.
Mitigating the Losses
Thrips are a significant pest issue for Florida’s crops and ornamental plants, causing both direct damage and the potential spread of plant viruses. Due to their small size and ability to hide in hard-to-reach places, an Integrated Pest Management (IPM) program should be implemented for effective control. By understanding the thrip’s lifecycle and employing control techniques such as scouting and a combination of control methods, growers can reduce the economic losses caused by these pests and ensure healthier, more productive plants.
For more information about thrips, access the following “Ask IFAS” publications:
THRIPS MANAGEMENT PROGRAM FOR HORTICULTURAL CROPS
WESTERN FLOWER THRIPS (FRANKLINIELLA OCCIDENTALIS [PERGANDE])
CHILLI THRIPS SCIRTOTHRIPS DORSALIS HOOD (INSECTA: THYSANOPTERA: THRIPIDAE)
Luis Rodriguez is the Polk County Small Farms and Pesticide Education Extension Agent. You can reach him at lrodriguezrosado@ufl.edu.
