Bug of the Month
Summer Scourge
Combat Chilli Thrips With Inspections & Insecticides
Chilli thrips (Scirtothrips dorsalis) are one of the most problematic pests in southern highbush blueberries in Florida, as well as other regions inside and outside the U.S. They represent a significant cost to growers throughout the spring, summer, and early fall in terms of chemical applications and, if not kept under control, a reduction in plant growth and yield.
Chilli thrips typically begin to appear on new flushes of growth late in the harvest season and reach a peak during the summer months after postharvest hedging. However, last season some growers also observed chilli thrips feeding on floral buds, resulting in bloom damage.
Adult chilli thrips are very small (less than 1/16 inch in length, smaller than flower thrips), with pale yellow bodies, incomplete stripes on the abdomen, and dark fringed wings (Figure 1). Their life cycle typically is between 18 and 20 days (from egg to adult), and adults live for 20 to 25 days.
Figure 1. Adult chilli thrips.
Credit: B. Panthi, UF/IFAS
Adults and larvae feed on young, tender plant tissues (usually foliage), using piercing and sucking mouthparts to remove plant cell contents. This results in bronzing and distortion. Leaf curling and cupping is often seen during periods of high population (Figure 2).
Figure 2. Chilli thrips feeding damage
Credit: D. Phillips, UF/IFAS
Managing chilli thrips includes careful monitoring and applications of insecticides that have proven to be effective in field trials. Monitoring should be routine and should start in spring prior to harvest. During periods of new flushes of foliage it can be performed by easily tapping foliage onto a white sheet of paper or a phone screen to look for live adults. This should be performed in areas throughout the field. Chilli thrips are not strong fliers and may initially appear in the field as “hot spots” that progress outward. When live adults are observed the application of appropriate insecticides should begin in that area, making sure to follow all label instructions and using a rotation of products with different modes of action to minimize the risk of resistance. Recent UF field trials conducted by Dr. Oscar Liburd and his lab found that Exirel® and Tres Oil + Exirel® were the most effective of the tested treatments in controlling chilli thrips, and Delegate® was the least effective. Also, a rotation of Exirel®, Transform®, and Apta® was the most effective of the different rotation treatments tested. In earlier trials Apta®, Assail®, Rimon®, and Sivanto® have also shown some effectiveness. Another round of field trials is planned for this summer by Dr. Liburd and his lab and will include plinazolin (which does not yet have a blueberry label) with and without adjuvant, APTA (a grower standard), two rates of Rimon, Entrust (an organic standard), and two rates of Wrath (a low rate and a high rate) as treatments.
In addition to insecticides, cultural practices can be an important part of chilli thrips management. Cultural practices include the removal of weeds and other plants that can serve as hosts for chilli thrips from the field and adjacent areas. A UF study of alternative chilli thrips hosts adjacent to Florida strawberry fields found that certain wild plant species including muscadine grape, Laurel cherry, sugarberry, Spanish needles, Peruvian water primrose, ragweed, sweetgum, and water oak all “showed consistent infestation with S. dorsalis during both summer non-crop seasons in this study” (S. Lahiri, C. Perry. 2025. Expanding Host Range of Invasive Pest Scirtothrips dorsalis Hood in the U.S.A. Advances in Entomology.)
Natural predators can also be part of an integrated chilli thrips management program. Natural enemies such as Orius insidiosus (the minute pirate bug, which feeds on all life stages of thrips), Amblyseius swirskii (predatory mites), and Geocoris spp. (big-eyed bugs) have all shown some effectiveness in managing chilli thrips populations.
Another area of chilli thrips management in blueberries is through plant genetics. The UF Blueberry Breeding Program has research underway to screen blueberry trial selections for susceptibility and resistance to chilli thrips damage to be able to select for traits that minimize damage from this significant and costly pest.
References:
O.E. Liburd, B.R. Panthi, D.A. Phillips. 2020. Chilli Thrips on Blueberries in Florida. UF EDIS Publication ENY-2053.
S. Lahiri, C. Perry. 2025. Expanding Host Range of Invasive Pest Scirtothrips dorsalis Hood in the U.S.A. Advances in Entomology.
CREDITS:
Dr. OSCAR LIBURD, Professor and Program Leader, Fruit and Vegetable Entomology, UF/IFAS
& DOUG PHILLIPS, blueberry Extension coordinator, UF/IFAS
