7/2/2013 - By Matthew Shultz

With the rapidly warming temperatures in May, Thrip insects will start to show up in the nursery. Thrips are in the Thysanoptera family, which means “Fringed Wing”. This family of insects can be divided into two separate groups, shoot feeders (flower, fruit and seed) and leaf feeders. These insects overwinter as adults in leaf litter and the upper portion of the soil. After emergence in the spring, the females insert eggs into newly expand­ing leaves and flower buds. The larvae hatch and go through two wingless larval stages before they pupate in the soil and emerge as adults. The larval stages of this insect are herbivores and feed on plant material, this is the life stage to focus on in the nursery, while the adults are sap and pollen feeders. The larvae use a scratching/rasping motion with their mouthpiece and actually scrap the surface of the leaf or flower.

Most damage isn’t detrimental to the plant, just aesthetically unpleasing, especially with flower feeders. The adults can move using a jumping motion from host plant to host plant, or be blown by the wind, so rapid outbreaks can occur if conditions are optimal. Control of this pest is often difficult, because they feed in tight flower buds and leaves and once the damage is seen it is often too late. To monitor for these pest, simply take a white notebook paper and hold it under the leaves and branches of the plant, shake the plant material over the paper and inspect the paper for the presence of thrips and mites. Preventative sprays are the best control op­tion, alongside a good IPM program. Use products such as Conserve, Flagship, Safari, Attain TR, BotaniGuard, Acephate, Imidacloprid, Carbaryl, or soaps and oils. There are several naturally occurring predators of this pest including Orius spp. and Amblyseius mites that growers should encourage to help control outbreaks.

By Matt Shultz, Horticultural Tech Support Specialist and Sales Representative, Harrell’s LLC and Marshall Horsman, Technical Services Manager, Harrell’s LLC.