Brown marmorated stink bug in California isn’t news since it’s been present in urban areas for a while. The breaking news is that brown marmorated stink bug is starting to make its way into agricultural production areas. Unfortunately, wherever brown marmorated stink bug takes up residence, it causes severe crop losses.
Established populations have been reported in urban areas of 16 California counties. Monitoring in agricultural orchards and vineyards began when established populations were noticed in urban areas. In 2017, brown marmorated stink bug began to cause damage in agriculture, infesting commercial almond and peach orchards. This trend of infestation has been much more severe in 2018. Multiple almond orchards reported brown marmorated stink bug infestation, leading to yield loss in a few cases, in the northern San Joaquin Valley.
Brown marmorated stink bug can reach very high numbers, and since adults and all immature stages (except the first instar) can actively feed on many fruits, losses could be severe. The bugs suck juices from fruits and seeds, creating pockmarks and distortions externally, as well as fleshy whitish tissues and corky spots that make fruit and vegetables unmarketable. Damaged flesh under the skin turns hard and pithy. Brown marmorated stink bug damages fruits (e.g., apple, pear, citrus, stone fruits such as peach, and fig), nuts (hazelnut and almond), berries, grapes, legumes, vegetables, and shade trees. Brown marmorated stink bugs are known for switching their hosts during the season. Therefore, host crops that are closer to alternate hosts (e.g., tree-of-heaven) may have more bug damage.
Brown marmorated stink bug travels long distances by hitching rides in vehicles or as stowaways when furniture or other articles are moved, often during winter months. As a result, most new infestations are found in urban areas, where they seek winter shelter and congregate in large numbers on outside walls or invade homes by entering through small openings. It is also a pest in home gardens. As numbers increase in urban areas, it is likely that they will move into nearby agricultural crops.
If you find a stink bug in your field, orchard, or vineyard that you suspect might be a new location for brown marmorated stink bug, place it in a container and carefully note where and when you collected it. Take the sealed container to your local UC Cooperative Extension office. Brown marmorated stink bug is about ¾ inch long and looks similar to other brown stink bugs such as the consperse stink bug, brown stink bug, rough stink bug, and spined soldier bug. None of the other bugs have white bands on their antennae that brown marmorated stink bug has. The white bands are present in immature stages as well.
Currently, research is documenting brown marmorated stink bug damage and how and when to monitor for them in various crops.
Californians can help in the fight against invasive species by learning and participating during California Invasive Species Action Week, June 2–10.