Julie Crook (OSU Extension, Hamilton County) and I spent a lovely afternoon yesterday “cruising” the Cincinnati Botanical Garden and zoo with Steve Foltz (Director of Horticulture) looking at their impressive plant displays and working with Steve on some diagnostics. During our walk-about, Steve pointed out an “old friend” scurrying beneath a goldenrain tree (Koelreuteria paniculata; Soapberry Family, Sapindaceae): a Goldenrain Tree Bug (Jadera haematoloma).
Steve is very familiar with this southern native; he helped me sort out an unexpected appearance of goldenrain tree bugs in Greater Cincinnati in 2012. I got several calls from arborists at around this time in 2012 about large numbers of “Boxelder Bugs” (Boisea trivittata) showing-up beneath goldenrain trees in Greater Cincinnati.
On the face of it, the phone reports didn’t seem too odd because boxelder bugs use their piercing/sucking mouthparts to penetrate plant seeds to extract food. They feed on a wide range of plant seeds beyond the samaras of their namesake host and goldenrain trees were beginning to produce seed when I started getting the bug reports.
However, a phone call from Steve and a follow-up visit revealed that we weren’t dealing with boxelder bugs; we were dealing with Goldenrain tree bugs. The mulch beneath several goldenrain trees at the zoo were "crawling" with the bugs.
This was unexpected because the bugs are native to the southeastern U.S. where they evolved to feed on various native members of Sapindaceae such as the Florida soapberry (Sapindus saponaria). The native hosts accounts for their common name of “soapberry bug.” They are also called “redshouldered bugs” with this descriptive common name referring to the red edges of the pronotum (the thoracic segment behind the head).
Goldenrain tree bugs belong to the same bug family (Rhopalidae) as boxelder bugs; they have the same elongated body shape and are about the same size. They also practice the same nuisance behavior as their boxelder brethren with large numbers appearing en mass on landscapes around homes with the adults trying to enter homes to overwinter.
Given their shared size, shape, and behavior, it's easy to see why goldenrain tree bugs may be mistaken for boxelder bugs. However, they differ in coloration and markings. The key to separating the two bugs is included in their scientific names. The specific epithet, "haematoloma," is Greek for "blood-fringed," and clearly describes the deep red "shoulders" on the goldenrain tree bugs. The specific epithet for boxelder bugs, "trivittata" is Latin for "three-striped" and describes the three reddish-orange lines on the pronotum.
Like boxelder bugs, goldenrain tree bugs use their long, piercing-sucking mouthparts to feed on seeds and sometimes on fruit. While the goldenrain tree bugs tend to focus their attention on plants that are in or related to the soapberry family, particularly goldenrain tree, they may also feed on the seeds of maple and ash and on the fruit of plums, cherry, peach, and grapes. As a seed-feeder, the bugs cause no harm to the health of trees. However, their feeding activity on tree fruit and strawberries has been known to reduce fruit quality.
Much of the literature focuses on southern states for the distribution of this native insect, particularly Florida where native soapberries are a common host. However, research studies have shown that subpopulations have rapidly evolved adaptations to take advantage of introductions of non-native hosts such as goldenrain tree which has become naturalized in the south. The adaptations include longer or short beaks to allow the bugs to better penetrate seeds and physiological changes that allow the bugs to detoxify plant defense chemicals produced by the new hosts.
Goldenrain tree bugs were commonly found in southern and central Ohio in 2012 and again in 2013 with their range extending to Wooster. They were also reported in Maryland and New Jersey. However, the bugs virtually disappeared from Ohio in 2014. Likewise, no bugs were reported in 2015 or 2016. It was speculated that the relatively harsh winters of 2013-14 and 2014-15 may have put the kibosh to this southern insects forays into the north. Of course, our observations yesterday demonstrated that all of the Ohio bugs weren’t wiped out. Given that we saw two generations per season during their past Ohio heydays, we may expect to see more bugs as the season progresses.