This study was released in 2014 and referenced the polar vortex that year, not in 2019. A study done by Virginia Tech researchers in 2014 found the extreme cold killed off 95% of the stink bugs they were using in the experiment, according to a report by the Washington Post. Researchers said they were still studying whether it had the same impact in other areas or on the larger stinkbug population outside of the ones they had gathered for the study.
Some insects can die from short periods of very cold weather, and cold winters typically producer lower insect numbers in the Spring, according to an Entoomologist with the National Pest Management Association. However, they say it's not likely to have a significant impact on pest populations.