The bagrada bug, referred to as an “invasive stink bug” by researchers, is often seen as a mating couple on brassica family plants. A native of the African and Asian continents, this insect first made its appearance in the western United States in 2008. Since then, its American range has spread east from Los Angeles County to Arizona and areas of southern Nevada, Utah, and west-central New Mexico. It has been found as far north as Monterey County.
The insect has orange and white markings on its body and can be mistaken for the harlequin bug; however, it is much smaller than the harlequin bug and is typically 5-7 mm long and 3-4 mm wide (see photo by Surendra Dara). Bagrada bugs tend to aggregate into swarms that cover plants and have become a significant pest of broccoli, cauliflower, cabbage, Brussels sprouts, and related crops. They are even found on wild mustard and alyssum, a commonly planted trap crop. They do not limit themselves to brassicas, however, and have also been found on green beans, peppers, radish, strawberries, and even Monterey pine.
The good news is that UC Cooperative Extension Crop Advisor Surendra Dara has conducted studies that show organic formulations of entomopathogenic fungi such as Beauveria bassiana is effective at managing the pest. Dara has also looked at Metarhizium anisopliae (strain F52) and Paecilomyces fumosoroseus (strain FE9901) and found that they caused good mortality or infection in bagrada bug adults.
Remember to always clear materials with your organic certifier before use.
Additional Source: Reed, D.A., J. C. Palumbo, T. M. Perring, and C. May. 2013. "Bagrada hilaris (Hemiptera: Pentatomidae), An Invasive Stink Bug Attacking Cole Crops in the Southwestern United States." Journal of Integrated Pest Management Volume 4, Issue 3, pages C1-C7.