- Author: Kathy Keatley Garvey
Vacaville resident James Moehrke was out geocaching last weekend in the Vaca Valley Parkway-East Monte Vista Avenue area of the city when he spotted some red-shouldered black bugs.
"There were many clusters, probably thousands of individuals, in the trees and a few on the ground," he recalled. Some were on deciduous trees and others on evergreen trees.
What were they?
At first glance, they looked like boxelder bugs.
We asked Steve Heydon, senior museum scientist at the Bohart Museum of Entomology, to identify them.
"Soapberry bug or Jadera haematoloma," Heydon said.
They're a close relative of the boxelder bugs.
The soapberry bug is also known as "the red-shouldered bug" or the "golden raintree bug." It's mostly black except for the red eyes and red shoulders. The nympths are primarily red.
They're seed predators and often found on lychee, longan, maples and soapberry trees.
Biologist Scott Carroll, affiliated with the Sharon Lawler lab at the UC Davis Department of Entomology, researches the insects. He lectured on soapberry bugs at the 2007 meeting of the Entomological Society of America, describing them as "excellent organisms for studying responses to global change, evolution in action, ecological speciation, development and behavior."
Some of the fastest rates of evolution recorded are from this group as they have evolved new races on introduced host plants, Carroll told ESA.
The soapberry bugs fascinated Moehrke and his fellow geocaching players. He took time out to photograph them.
And yes, he found the treasure, the cache.
Along with lots of red-shouldered black bugs.