HOMESTEAD, Fla. – Short-spined thrips, an invasive insect species scientifically known as Thrips parvispinus, were first detected in Florida in 2020. Since then, the insect has been found in Georgia, the Carolinas, Colorado, Pennsylvania, Texas, New York, and parts of Canada.

Short-spined thrips and other species of thrips are incredibly difficult to see with the naked eye at about 0.5 to 1.5 millimeters in length. They feed on a wide variety of plants including ornamental plants like hibiscus and jasmine and fruit and vegetable crops like peppers, beans, strawberries and eggplants. Adults and larvae cause damage by feeding on leaves and flowers; common signs and symptoms include silver scars on foliage, distorted or deformed plant growth, yellow or brown leaves, premature leaf drop, and scarring on fruits.

The damage that thrips cause is similar to damage caused by other pests which can lead to more severe infestations and economic loss. One South Florida farmer lost an entire pepper crop yield to thrips costing them $1 million, said Alexandra Revynthi, assistant professor of ornamental entomology and acarology at the University of Florida.

“When we found (short-spined thrips) in Florida, we started working on research immediately in order to assist the ornamental industry which is very active and large in South Florida,” she said. “It is a pest that you don’t have the luxury to allow it to grow its population. It’s a very aggressive pest that is very small. It lays its eggs inside the leaves (of a plant) so the eggs cannot even be seen with a hand lens or under a microscope. We only see the emergence of the larvae – and that’s late.”

In December, Revynthi and her research group published the first complete biological roadmap of the pest, discovering the biological traits that have allowed short-spined thrips to proliferate in Florida and beyond. One finding pertains to the pest’s lifecycle – short-spined thrips pupate, or enter the transitional phase between larvae and adult, in the soil and emerge from the soil as adults.

“This information is very important because it tells us that if we want to break the cycle, we can of course do so by treating the canopy and leaves, but we also have the opportunity to do so by treating the soil and preventing the insect from completing its lifecycle and emerging as an adult,” Revynthi said.

Additionally, the researchers found that South Florida’s climate is perfect for thrips, as the insect can complete its lifecycle in less than 13 days and reach peak reproduction rate at the region’s average temperature of about 80 degrees. Short-spined thrips are unable to survive long periods of cold, suggesting that winter offers relief from the pest. The study also demonstrated that females can produce male offspring without mating, important for understanding how large populations can be established with only a few individual insects. Thrips also require live plants for survival.

Because of the small size of the pest, it can be difficult to monitor for it. Revynthi said a feasible method for monitoring involves taking a clipboard or other hard surface and adding a white piece of paper on top. Then, place the board with the paper beneath the plant leaves and gently hit the leaves on top of the paper. The thrips will fall to the piece of paper, and it will be easy to see them. Sticky traps can also be deployed.

“You (won’t) know which particular species you have – there are many species of thrips in the United States,” she noted. “The next step will be to collect the species and send them for identification to an entomologist so that they can confirm the species and recommend the next steps.”

Recommended pest management will depend on the size of the population of thrips and if one is close to harvest. Combining multiple management tools is recommended, Revynthi said. The current best identified management for thrips is chemical control, biological control, trapping and capturing, and pruning for ornamental plants.

“(Researchers) are still trying to make progress on the usual biological control, which is to use live organisms to mitigate the insect, but we are also looking at tolerant or resistant cultivars of peppers and other ornamentals,” she added.

Producers are encouraged to monitor crops for outbreaks and implement integrated pest management if infestation occurs.